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4 rMAY - 8 

Cosy. 1975 

EMISSIONS CONTROL 
OF 

ENGINE SYSTEMS 


CONSULTANT REPORT TO THE: 
Committee on Motor Vehicle Emissions 
Commission on Socioteehnieal Systems 
National Research Council 


SEPTEMBER 1974 



l.S. ENVIRONMENTAL PROTECTION AGENCY 
Office of Air and Waste Management 
Office of Mobile Source Air Pollution Control 

















CONSULTANT REPORT 


to the 

Committee on Motor Vehicle Emissions 
Commission on Sociotechnical Systems 
National Research Council 
on 

EMISSIONS CONTROL OF ENGINE SYSTEMS 


PREPARED BY: 

James E. A. John, Chairman, Engine Systems 

Naeim A. Henein 

Ernest M. Jost 

Henry K. Newhall 

David Wulfhorst 

John W. Bjerklie, Chairman, Alternatives 
William J. McLean 
Charles Tobias 
David Gordon Wilson 


Washington, D.C 
September 1974 




NOTICE 



This consultant report was prepared by a Panel of Consultants at 
the request of the Committee on Motor Vehicle Emissions of the National 
Academy of Sciences. Any opinions or conclusions in this consultant re¬ 
port are those of the Panel members and do not necessarily reflect those 
of the Committee or of the National Academy of Sciences. 

This consultant report has not gone through the Academy review 
procedure. It has been reviewed by the Committee on Motor Vehicle Emis¬ 
sions only for its suitability as a partial basis for the report by the 
Committee. 

The findings of the Committee on Motor Vehicle Emissions, based 
in part upon material in this consultant report but not solely dependent 
upon it, are found only in the Report by the Committee on Motor Vehicle 
Emissions of November 1974. 


ii 





PREFACE 


The National Academy of Sciences, through its Committee on Motor 
Vehicle Emissions (CMVE), initiated a study of automobile emissions- 
control technologies at the request of the United States Congress and 
the Environmental Protection Agency (EPA) in October 1973. To help 
carry out its work, the CMVE engaged panels of consultants to collect 
information and to prepare consultant reports on various facets of mo¬ 
tor vehicle emissions control. This Consultant Report on Emissions 
Control of Engine Systems is one of five consultant reports prepared 
and submitted to the Committee in connection with the Report by the 
Committee on Motor Vehicle Emissions of November 1974. The other con¬ 
sultant reports are: 

An Evaluation of Catalytic Converters for 
Control of Automobile Exhaust Pollutants, 

September 1974 

Emissions and Fuel Economy Test Methods and 
Procedures, September 1974 

Field Performance of Emissions-Controlled 
Automobiles, November 1974 

Manufacturability and Costs of Proposed Low- 
Emissions Automotive Engine Systems, November 
1974 

These five consultant reports are NOT reports of the National Academy 
of Sciences or its Committee on Motor Vehicle Emissions. They have 
been developed for the purpose of providing a partial basis for the 
report by the Committee as described more fully in the cover NOTICE. 

ACKNOWLEDGEMENTS 

The authors would like to thank Drs. Robert F. Sawyer and 
Nicholas P. Cernansky for their contributions to this consultant 
report. 


iii 






CONTENTS 


Conclusions. 1 

1. Introduction. 3 

2. Modifications to Conventional Reciprocating Spark-Ignition 

(S.I.) Engines. 5 

3. Conventional Spark-Ignition Engine with Oxidation Catalyst-- 

1975 Standards. 10 

4. Potential of Conventional Engines with Oxidation Catalysts... 13 

5. Air/Fuel Mixture Preparation. 18 

6. Lean Burn Systems. 62 

7. Dual Catalyst Systems. 67 

8. Three-Way Catalyst with Feedback. 80 

9. Rotary Engines. 90 

10. Stratified-Charge Engines. 100 

11. Diesel Engines. 137 

12. Alternative Power Plants for Automobiles. 179 

13. Alternative Fuels. 214 

References. 239 

Appendices 

A. Organizations Contacted by Members of the Panel of Consultants 

on Engine Systems. 256 

B. Organizations Contacted by Members of the Panel of Consultants 

on Alternatives. 259 

iv 


















TABLES 


Table No. Page No. 


Summarization of the Work of the Panel on 

Internal Combustion Engines. 2 

2.1 Federal Exhaust-Emission Standards. 6 

2.2 Effect of Engine Modifications on Emissions. 7 

4.1 Results of 1975 California Certification. 14 

4.2 Exhaust Emission Test Summary California Division 

of Highways Underfloor Converter Fleet. 15 

4.2 "In Service" Fuel Economy Summary California 

Division of Highways Underfloor Converter Fleet. 16 

5.1 Test Results of a 1973 Dodge Monaco. 28 

5.2 Cylinder-to-Cylinder Distribution Spreads. 37 

5.3 Comparison of Air/Fuel Ratio Distribution with 

and without Vapipe - 1.8 Litre. 40 

5.4 Evaluation of a Carburetor with Ultrasonic Fuel 

Dispersion Used on a Plymouth Duster. 41 

6.1 1974 Dodge, 360 CID, 4,500 lbs (Ethyl tests).... 62 

6.2 Results with the Dresserator on the 1975 FTP.... 65 

7.1 Experimental Results - Dual Catalyst System. 68 

7.2a Prototype 1977 Dual Catalyst System Performance 

350 CID, 5,000 lb, EGR, Air, '75 FTP Low Mileage 70 

7.2b 18 Car Fleet 1977 Dual Catalyst System Performance 71 

7.3 1977 Dual Catalyst - Closed-Loop System Performance 73 

7.4 Results of GEM 68 System 76 

7.5 Questor System on 1971, 400 CID Pontiac Catalina 78 

8.1 Results of Three-Way Catalyst with EFI and 

Feedback. 82 


v 















Table No. Page No. 

8.2 Data on a Vega with Three-Way Catalyst, EFI 

and Feedback. 85 

8.3 Comparison of Various Control Schemes (1.9 L 

Engine) All Cars Equipped with L-jetronic. 86 

8.4 Results of Three-Way Catalyst with MFI. 87 

8.5 GM Results with Advanced Design Carburetors, 

Feedback and Three-Way Catalyst. 88 

9.1 Exhaust Emissions of the 1974 Mazda with Rich 

Thermal Reactor. 91 

9.2 Typical Deterioration Factors of Thermal 

Reactor-Equipped Rotary Engines. 94 

9.3 Emissions Summary. 95 

9.4 Rotary with Lean Reactor. 96 

9.5 Emission and Fuel Consumption Characteristics 
of an Experimental Open-Chamber Stratified- 

Charge Rotary Engine. 97 

10.1 Emissions and Fuel Economy of Turbocharged 

TCCS Engine-Powered Vehicle 116 

10.2 Fuel Specifications for TCCS Emissions Tests.. 117 

10.3 Honda Compound Vortex-Controlled Combustion- 

Powered Vehicle Emissions. 124 

10.4 Emissions and Fuel Economy for Chevrolet Impala 

Stratified-Charge Engine Conversion 125 

10.5 Single-Cylinder Low Emissions Engine Tests.... 133 

10.6 Volkswagen Large-Volume Prechamber Engine 

Emissions. 135 

11.1 Mass Emissions and Fuel Economy from LDV 

Diesel Engines - 1975 FTP 138 

vi 















Table No. Page No. 

11.2 Effect of Injection Timing on Emissions 
from Perkins 154 Engine in Ford Zephyr 

Car (CVS Cycle). 145 

11.3 Aldehydes and Ammonia Emissions from Different 

Types of Cars. 153 

11.4 Comparison Between Opel Diesel and Gasoline 

Cars. 158 

11.5 Fuel Economy in Taxi Application. 161 

11.6 Comparison Between Diesel and Gasoline Fuels.. 161 

11.7 Initial and Maintenance Costs and Performance 

of Mercedes 1975 Cars. 163 

11.8 Comparison Between Exterior and Interior 
Noise Levels of Diesel- and Gasoline-Powered 

Cars. 171 

11.9 Comparison of Odor from Diesel- and Gasoline- 

Powered Cars. 175 

12.1 Steam Engine Characteristics. 188 

12.2 Stirling Engine Description. 193a 

12.3 Batteries for Electrically Driven Vehicles.... 204 

13.1a Cost of Alternative Fuels. 218 

13.1b Cost of Alternative Fuels. 219 

13.2 Physical Properties of Iso-octane and Methanol 227 

13.3 Test Data for 157 c Methanol-Gasoline Blend. 233 

13.4 Federal Test Procedure Emissions with Hydrogen 

Supplemented Fuels. 235 

13.5 Effect of Vareb-10 on Cold-Start Emissions.... 237 


vii 

















FIGURES 


Figure No. Page No. 

5.1 The Relationship of Typical Engine Emissions 

and Performance to Air/Fuel Ratio. 19 

5.2 Air/Fuel Ratio Control. 21 

5.3 Idle Speed Circuit. 22 

5.4 Fuel Metering Curve. 23 

5.5 Air/Fuel Ratio Distribution. 25 

5.6 Variable Venturi Carburetor. 27 

5.7 Fuel Droplet Size Distribution. 29 

5.8 Sonic Carburetor Principle. 31 

5.9 Ford Motor Co. Estimate of Induction System 

Mixture Quality Trends under Hot Operating 
Conditions. 32 

5.10 Ford Motor Co. Estimate of Induction System 

Mixture Quality Trends under Cold-Start and 
Driving Conditions. 33 

5.11 Ethyl Corporation's Rectangular Hot Box Man¬ 
ifold for a 360 CID Plymouth. 36 

5.12 Location of Vapipe. 39 

5.13 Ultrasonic Carburetor. 42 

5.14 Electronic Fuel Injection. 44 

5.15 Air Mass Sensor. 47 

5.16 K-jetronic System. 50 

5.17 (No title). 52 

5.18 Oxygen Sensor. 56 

5.19 Sensor Characteristic. 58 


viii 























Figure No. Page No. 

5.20 Sensor Output. 59 

5.21 Optimizer Control. 60 

7.1 Durability Data. 68 

7.2 AMA Durability Test - Oxidizing and Reducing 

Catalyst. 69 

7.3 Effect of Getter on Inlet CO and 02. 74 

7.4 Typical Net NOx Conversion. 75 

8.1 Conversion Efficiency of a Three-Constituent 

Catalyst. 81 

8.2 4-Cylinder Engine, 1.9 Liter, L-jectronic... 83 

8.3 Catalyst Durability. 84 

9.1 HC Conversion Efficiency Requirements. 92 

9.2 Comparison of NOx and Fuel Consumption. 98 

10.1 Ford Proco System. 106 

10.2 Ford Proco Engine Fuel Economy and Emissions 107 

10.3 Texaco TCCS Engine. 110 

10.4 Texaco Controlled Combustion System. Ill 

10.5 Texaco TCCS-Powered Cricket Vehicle. 113 

10.6 Turbocharged Texaco TCCS M151 Vehicle. 114 

10.7 3-Valve Prechamber Engine Concept. 119 

10.8 Honda CVCC Engine. 122 

10.9 Fuel Economy Versus HC Emissions for 3- 

Valve Prechamber Engines. 126 

10.10 Fuel Economy Versus NOx Emissions for Honda 

CVCC-Powered Vehicles. 128 

ix 























Figure No. 


Page No. 


10.11 Ford Divided Chamber. 131 

10.12 Comparison of Conventional and Divided 

Combustion Chamber NOx Emissions. 132 

10.13 400 CID Large Volume Prechamber Engine. 134 

11.1 Emissions from Diesel-Powered Cars 

(1975 FTP). 139 

11.2 Effect of EGR on the Emissions from a 

Mercedes Diesel Engine. 141 

11.3 Effect of EGR on Opel Rekord Diesel Car 

(1975 FTP). 143 

11.4 Effect of Injection Timing on Emissions 

(1975 FTP). 144 

11.5 Airborne Particulates Emitted from Diesel- 

and Gasoline-Powered Cars. 147 

11.6 Benzo(a)Pyrine Emissions from Different 

Automotive Engines According to 1975 FTP- 

Cold Start. 149 

11.7 Benzo(a)Pyrine Emissions from Different 

Automotive Engines at 60 mph Steady Running 
Conditions. 150 

11.8 Sulfur Compounds Emissions from Different 

Cars. 151 

11.9 HCHO Emissions for the Modified Federal Cycle 

Cold Start (MFCCS). 154 

11.10 HCHO for 60 mph Steady Running Conditions.... 155 

11.11 Comparison of Fuel Economy at Road Load for 

Mercedes Diesel and Gasoline Cars. 157 

11.12 Comparison of mpg for Different Cars under 

Steady-State Conditions. 159 

11.13 Comparison of mpg for Different Cars under 

City, Suburban and Average Driving Condi¬ 
tions. 160 


x 



















Figure No. 

11.14 

11.15 

11.16 

11.17 

11.18 
12.1 

12.1 

12.2 

12.3 

13.1 

13.2 


Comparative Driveability of Diesel- 
Powered and Other Cars. 

Exterior Noise Levels from Different Cars... 

Exterior Noise Levels from Different Cars... 

Comparison of Exterior Noise Levels for 2.2 
Liter Mercedes Gasoline and Diesel Cars. 

Interior Noise Levels from Different Cars... 

Rear View of VW with Carter Steam Engine 
Mounted; The Prime Mover Showing the 4 
Cylinder. 

The Boiler-Burner Assembly. 

Flow Chart. 

Fuel Economy-Alternative Engines. 

U.S. Petroleum Supply and Demand. 

Emissions Data for Alcohol-Gasoline Blends 
(1975 FTP). 


Page No. 

166 

167 

169 

170 
173 

189 

190 
192 
213 
217 

232 


xi 
































































































































































CONCLUSIONS 


1. From the viewpoint of fuel economy, at least on an urban-type 
driving cycle, the diesel and stratified-charge engines appear 
most attractive. Potential problem areas for these engines that 
must be resolved before large-scale introduction include smoke 
and particulates (and possible adverse health effects), odor, 
noise and a lower performance than a conventional spark-ignition 
(S.I.) engine due to lower power-to-weight ratio (especially 
with the diesel). 

2. The three-way catalyst system with feedback control appears to 
offer benefits as far as maintainability and driveability are 
concerned, with only slight loss of fuel economy due to emissions 
control. The dual-catalyst (Gould) system provides a tolerable 
interim approach until the three-way catalyst, feedback system is 
ready for producticn. 

3. Regarding standards for 1978, lowering of N0 X emissions levels 
from 1.0 to 0.4 g/mi appears to exact a penalty in fuel 
consumption of up to 35% by excluding the diesel engine. Possible 
benefits to health should be weighed against this cost. 

4. There are no alternative, non-internal combustion engines that 
could be available in mass production for standard-size 
automobiles before the 1980's. 

5. The accompanying table summarizing the work of the Panel of 
Consultants on Internal Combustion Engines presents emissions 
levels achievable in certification for various systems, as well 
as fuel economy penalty (or advantage) due to emissions controls 
as measured on the Federal CVS/CH driving cycle. Projected 
dates of availability for mass production of each system are also 
given in the table. 


1 



2 


Fuel Economy 

Penalty Availability for 

(relative to 1967) Mass Production 


Emissions 

Levels System 


0.41-3.4-2.0 

Oxidation catalyst and exhaust gas 
recirculation and engine modifications 

5% 

1976 


Lean burn engine 

5% 

1977 


Diesel 

-(25%-40%) 

Now 


Stratified charge - 

small volume prechamber with reactor 

0%-10% 

Now 


Stratified charge - 

direct fuel-injected with catalyst 

-(25%-40%) 

1980 


Wankel with lean reactor 

5%-10% 

1976 

0.41-3.4-1.0 

Diesel and exhaust gas recirculation 

-(20%-35%) 

1976 


Dual catalyst (e.g., Gould) system 

5%-10% 

1977 


Three-way catalyst and feedback 

0%-5% 

1978-80 


Stratified charge - 

small volume prechamber with reactor 

10%-20% 

Now 


Stratified charge - 

direct fuel-injected with catalyst 

-(15%-20%,) 

1980 


Wankel with lean reactor and exhaust 
gas recirculation 

20% 

1976 

0.41-3.4-.4 

Dual catalyst (e.g., Gould) system 

5%-10% 

1977 


Three-way catalyst and feedback 

07.-5% 

1978-80 


Stratified charge - 

small volume prechamber with reactor 

2 5%-30%, 

Now 


Stratified charge - 

direct fuel-injected with catalyst 

0 

1980 






1. INTRODUCTION 


The Consultant Report on Emissions Control of Engine Systems 
represents the findings of the Panel on Internal Combustion Engines 
and the Panel on Alternative Engines. The first Panel was charged 
with evaluating the potential of conventional, spark-ignition 
internal-combustion engines and other internal-combustion engines, 
such as the rotary, diesel and stratified-charge engines, for meeting 
strict levels of oxides of nitrogen (NO ) control in conjunction 

X 

with specified levels of unburned hydrocarbons (HC) and carbon 
monoxide (CO). The second Panel was charged with assessing the 
potential of alternative, more advanced automotive engines, such as 
the gas turbine, Stirling, and Rankine power plants, for meeting 
similarly strict levels of emissions control. Primary consideration 
was to be given to cost, in terms of fuel consumption, associated 
with the achievement of various NO^ levels by the different engine 
systems. The Panels were to be concerned with emissions levels 
attainable in certification with vehicles tested according to the 
1975 Federal Test Procedure (FTP). Durability of the engine - and 
emissions-control systems for 50,000 miles was of importance, with 
mileage accumulation according to the certification test procedure. 
Likewise, fuel economy was to be evaluated on vehilces being driven 
on the FTP. Other Consultant Reports to the CMVE are to deal with 
performance in customer use, alternate testing procedures, catalytic 
converters, and the manufacturability and costs of low-emissions 
engine systems. 

The CMVE, for the purpose of this study, is interested in 
engines and systems that could be available in mass production by 
the late 1970's and early 1980's. 

For the 1975 model year, well over 957, of the new vehicles 
sold in the United States will continue to be powered by conventional, 
reciprocating spark-ignition engines with add-on devices to control 
emissions to the required levels. Small numbers of rotary. 


3 


4 


stratified-charge and diesel-powered vehicles will also be available. 
Due to manufacturing lead times and constraints in the tooling 
industry, it is clear that the conventional engine will continue 
to dominate the market, at least up to the 1980's, in spite of 
potential advantages that one or the other alternatives may have in 
terms of emissions, economy, maintainability, performance or cost. 

For this reason, the first sections of this report will deal with 
the conventional engine, and the various add-on devices and engine 
modifications that have the potential for meeting increasingly 
stringent NO levels. Later sections of the report will cover, in 
depth, the rotary, stratified-charge and diesel internal combustion 
engines. 

The current status of development of alternative, non-internal- 
combustion engines is such that at least another generation of 
development will be required before any of these will have reached 
the stage of being considered a suitable prototype for manufacture. 
Whereas several such engines have been run in automobiles; for 
example, the gas turbine, Stirling, steam and electric engines, 
several major developments are necessary before these power plants 
would be ready for mass production. The Panel of Consultants estimates 
that 1982 is the earliest one of the alternate engines, the gas 
turbine, would be ready for limited production, and even then only if 
several technological advances are achieved. For this reason, the 
sections of this report dealing with alternative engines must be 
considered of less direct relevance to the goals of the CMVE in 
their study as compared to the sections on the internal-combustion 
engine. 


2. MODIFICATIONS TO CONVENTIONAL RECIPROCATING 
SPARK-IGNITION (S.I.) ENGINES 

Up to the 1974 model year, auto manufacturers for the most part 
have met the exhaust-emissions standards by means of modifications to 
the conventional engine. As a reference, the federal and California 
standards that have been achieved in certification, all converted to the 
1975 FTP, as well as future emissions standards, are given in Table 2.1. 
Changes to achieve the specific standards, up to model year 1974, have 
included alterations in spark timing, reduction in compression ratio (CR), 
use of leaner air/fuel (A/F) ratios, shorter choke times, improvements 
in carburetion, exhaust-gas recirculation (EGR), use of air pumps and air 
injection to promote exhaust reactions, and inlet air preheating. The 
primary effects of these modifications on exhaust emissions are summarized 
in Table 2.2 below. 

Such techniques have been successful in achieving reductions in 
exhaust emissions from those of an uncontrolled 1967 vehicle of approxi¬ 
mately 80% in hydrocarbons, 70%, in carbon monoxide and 50% in oxides of 
nitrogen. Accompanying these reductions in emissions has been an increase 
of vehicle fuel consumption. Factors such as spark retard, reduction of 
compression ratio and exhaust-gas recirculation have tended to reduce 
engine efficiency and, hence, degrade fuel economy. Alternately, reduc¬ 
tions of choke times and improvements in carburetion have a beneficial 
effect on fuel economy. 

The overall fuel economy degradation on a sales-weighted 

average due to emissions controls, from 1967 to 1973 or 1974, is between 
1 2 3 * 

10%-15% ’ ’ based on the vehicles being tested on the urban federal 
driving cycle. Greater losses have been felt in larger cars, only small 
decreases or even benefits in smaller cars. 

There are several reasons why small cars have not shown the 
same increase of fuel consumption as standard or large-size cars. 

First, with the lower exhaust flows of smaller cars, the mass emissions 

of NO and CO of uncontrolled small cars (less than 3,000 lbs) were 

x 4 

less than those of larger cars (greater than 4,000 lbs'). This 


-'References are listed at the end of the report (page 139). 


5 



6 


TABLE 2.1 

Federal Exhaust-Emission Standards 

HC(g/mi) CO(g/mi) NO (g/mi) 

X 


1967 (Precontrol) 12 

79 

6 

1968 

6.2 

51 

NR* 

1970 

4.1 

34 

NR 

1972 

3 

28 

NR 

1973,1974 

3 

28 

3.1 

1975,1976 

1.5 

15 

3.1 

1977 

0.41 

3.4 

2.0 

1978 

0.41 

3.4 

0.4 

t required 

California Exhaust 

-Emission Standards 


1972 

2.9 

28 

3.1 

1974 

2.9 

28 

2.0 

1975,1976 

0.9 

9 

2.0 







7 

TABLE 2.2 

Effect of Engine Modifications on Emissions 


Spark Retard 

HC 

Reduce 

CO 

N0 X 

Reduce 


Reduce CR 

Reduce 

— 

Reduce 


Lean A/F 

Reduce 

Reduce 

Increase 

(then decrease if 

EGR 

Increase 

— 

Reduce 

beyond A/F = 16) 

Air Injection 

Reduce 

Reduce 

— 


Shorter Choke 
Time 

Reduce 

Reduce 

— 


Air Preheat 

Decrease 


Increase 



8 


has meant that less EGR, for example, has been necessary to reduce 
NO^ to required levels. 

Further, pre-controlled small cars typically ran with richer 
calibrations than standard or large cars. Greater improvements were 
then realized with leaning out the carburetion. Finally, fuel¬ 
metering technology for larger cars has been superior to that of small 
cars. The imposition of emissions controls has required large 
improvements in fuel metering for small cars, some manufacturers 
going to mechanical or electronic fuel injection. Thus, these factors 
have all tended to improve economy of small cars, canceling out losses 
due to other engine modifications to achieve emissions control. 

The most important factors that cause increased fuel 

consumption due to emissions control have been spark retard, decrease 

of compression ratio, and EGR. Reduction of one compression ratio, 

for example from 9:1 to 8:1, has the effect of increasing fuel 

consumption by 37 0 -57 0 . A comparable fuel economy penalty has been 

incurred with the use of spark retard to achieve HC and NO control. 

x 

Further, the use of off/on EGR to achieve NO levels of 3.1 g/mi 

x 

called for in 1973 and 1974 models has brought about an approximate 
57 0 -67o decrease of fuel economy. 

It is important to realize that exhaust emissions are 
influenced by many engine variables; for good economy and low 
emissions, control systems must be optimized. For example, running 
lean provides benefits in fuel economy, but may result in higher NO 

x 

emissions, necessitating the use of EGR. The use of EGR, requiring 
mixture enrichment to retain driveability, also permits an increase 
of spark advance, which may recover some of the fuel economy 
degradation caused by using EGR.~* 

In general, engine modifications, such as spark retard and 
EGR or the addition of an air pump, adopted to lower emissions from 
1974 levels to those of 1975 models for the 49 states or even 


9 


California, have the effect of degrading both fuel economy and 
driveability. Thus, whereas manufacturers are certifying some 
vehicles with only engine modifications for production at 1975 federal 
levels or at 1975 California levels, such vehicles incur a fuel 
economy penalty of 5%-107 o relative to 1974 vehicles. For the most 
part, such systems are backup to their primary, first-choice system 
which features the use of an oxidizing catalytic converter. 


3. CONVENTIONAL SPARK-IGNITION ENGINE WITH 
OXIDATION CATALYST - 1975 STANDARDS 


A very large percentage of 1975 models sold in the United 

States, both domestic and foreign made, will feature the use of an 

oxidation catalyst to clean up the exhaust hydrocarbons and 

carbon monoxide. Several different configurations of catalyst and 

system will be used. For example, General Motors will generally 

employ an under-floor pelletized catalyst bed, whereas Ford will use 

a monolith located nearer to the engine. Ford will use an air pump 

on all catalyst-equipped cars; General Motors and Chrysler will use 

air pumps in California cars, but only on a small number of 49-state 

cars. Whereas Chrysler and Ford will use about the same carburetion 

as 1974, General Motors will run at about A/F ratio = 16, leaner 

than 1974. All catalyst-equipped cars will use low lead (91 RON) 

fuel (.05 g/gal) to prevent catalyst poisoning. Nineteen seventy-five 

emissions-control systems will also feature improved start-up 

procedures to permit rapid fuel evaporation, high energy breakerless 

electronic ignition to provide more reliable ignition, and EGR to 

control NO . 

x 

At present, it appears that virtually all 1975 models equipped 
with oxidizing catalytic converters will be certified for production. 
Catalyst durability is such that no American-made models and only some 
European models will require catalyst changes in 50,000 miles. With 
lead-free fuel and breakerless ignition, there appears to be very 
little deterioration in engine emissions for 50,000 miles. The chief 
difficulty is deterioration in HC control with the catalytic converter. 
Whereas HC conversion efficiencies are well over 95% at low mileage, 
they deteriorate to 607 o -70% at 50,000 miles. 

Fuel-economy gains are to be experienced with the use of 
oxidation catalysts. To some extent, the car can now be tuned for 
optimum economy, with the catalyst cleaning up the resultant HC and CO 
emissions, rather than tuning for minimum emissions and losing 
economy. Chief economy gains are to be realized with elimination 


10 


11 


of some of the spark retard used in previous model years to control 

HC. The limitation on the amount of spark advance with catalytic 

systems is not resultant HC levels but the octane rating of the fuel 

used and the resultant problem of knock. With more spark advance, 

proportional EGR systems more closely tailored to the engine 

requirements, better cold-start performance and, in some cases, 

leaner-carburetion, large economy improvements are possible. On the 

basis of data taken from durability certification cars, General 
6 

Motors reports the following improvements in fuel economy, comparing 
1975 vs 1974 49-state cars in the federal test procedure: 

Including Mix Change + 19.8% 

Eliminating Mix Change* + 21.1% 

*Assumes 1975 mix (75%, large cars) for 1974 production, where 
actual 1974 production was 80%, large cars. 

A comparison of fuel economy for GM California 1975 cars vs 49-state 
cars shows an approximate 5%, degradation in fuel economy sales- 
weighted miles per gallon (SWMPG) for the California cars, due 
primarily to the use of the air pump and increased EGR in California 
cars. Again, results are from certification tests run on the FTP. 

Somewhat lesser fuel economy improvements in certification 
have been reported by the other American and foreign manufacturers. 
For example, Chrysler and Ford anticipate a 5%, improvement in economy 
over 1974 vehicles. It must be remembered that the above figures 
represent comparisons between different model years of the same 
manufacturers. Comparisons of the SWMPG of American manufacturers 
for 1974 models showed the following: 

GM 
Ford 

Chrysler 


10.29 

11.63 

11.10 


12 


The use of catalytic converters on small cars has not resulted 
in a fuel economy improvement, primarily because such cars did not 
suffer the penalty due to engine modifications of the large cars. 
Therefore, foreign manufacturers report fuel economy for 1975 vehicles 
roughly equivalent to that of 1974 models. 

It is significant to note that with the use of the catalytic 
converter, most, if not all, of the 10% to 15% fuel economy penalty 
attributed to emissions controls has been recovered. 


4. POTENTIAL OF CONVENTIONAL ENGINES WITH OXIDATION CATALYSTS 


In examining the potential of conventional systems for meeting 

the current 1977 standards of 0.41 g/mi HC, 3.4 g/mi CO and 2.0 g/mi 

NO , it is of interest to look first at results achieved by 1975 

California certification cars, tuned to meet levels of 0.9 g/mi HC, 

9.0 g/mi CO and 2.0 g/mi NO . Table 4.1 shows data from all the 

x 

vehicles that have, at this date, been made available to the Panel of 
Consultants and have completed California certification. The quoted 
emissions values include 50,000-mile deterioration factors, applied 

g 

in the required certification test procedure. 

Caution must be exercised in drawing conclusions from Table 4.1 
manufacturers must aim at targets well below the standards to ensure 
with some degree of confidence that a satisfactory mix of vehicles 
will pass certification and be available to the market. Nevertheless, 
these vehicles were not tuned to meet 1977 levels, but rather the 
higher California 1975 levels, so significant reduction in emissions 
are possible (below those of Table 4.1). 

Very little data are available on systems tuned to meet 1977 
levels. General Motors has had two fleets of Oldsmobiles in service 
with the California Highway Department. Both fleets were tuned to 
meet 1977 levels, and equipped with oxidation catalysts, one fleet 
with air pumps, one without. Results are shown in Table 4.2. Mileage 
accumulation for these data were not according to the AMA durability 
schedule of the FTP. 

The data shown in the above mentioned tables provide 
convincing evidence that 1977 levels can be achieved by model year 
1977. One method of achieving the required reductions in emissions 
from California 1975 certification would be via engine modifications, 
such as spark retard, with the loss of fuel economy. However, 
improvements are available which would not necessarily increase fuel 
consumption over that of a 1975 California car. 


13 


14 


TABLE 4.1 


Results of 1975 California Certification 


Manufacturer 

Vehicle 

HC 

CO 

N0 X 

MPG 

1 . 

GM 

Vega, 2,750# I.W., 140 CID 
Automatic 

0.4 

6.8 

1.6 

20.1 

2. 

GM 

Cutlass, 4,500#, 350 CID, 
Automatic 

0.4 

2.3 

1.4 

12.6 

3. 

GM 

Delta 88, 5,000#, 350 CID 

0.7 

6.7 

1.6 

12.4 

4. 

AMC 

Hornet 232 A, 3,500# 

0.28 

7.5 

1.5 

15.6 

5. 

AMC 

Hornet 258 A, 3,500# 

0.18 

5.9 

1.5 

14.4 

6 . 

AMC 

Hornet 232 M, 3,500# 

0.46 

7.3 

1.9 

13.8 

7. 

AMC 

Gremlin 232 A, 3,000# 

0.22 

6.2 

1.5 

16.8 

8. 

AMC 

Pacer 258 M, 3,500# 

0.26 

6.3 

1.9 

14.9 

9. 

AMC 

Matador 304 A, 4,500# 

0.46 

3.7 

1.9 

13.1 

10. 

AMC 

Gremlin 304 M, 3,500# 

0.49 

6.3 

1.7 

13.0 

11. 

AMC 

Hornet 304 M, 3,500# 

0.64 

7.4 

1.9 

12.8 

12. 

AMC 

Matador 304 A, 4,500# 

0.23 

3.6 

1.9 

12.3 

13. 

AMC 

Matador 2V-360 A, 4,500# 

0.51 

4.3 

2.0 

11.9 

14. 

AMC 

Matador 2V-360 A, 4,500# 

0.36 

3.2 

1.9 

11.9 

15. 

AMC 

Matador 2V-360 A, 4,500# 

0.45 

2.9 

1.6 

11.6 

16. 

AMC 

Matador 4V-360 A, 4,500# 

0.42 

2.6 

1.9 

11.7 

17. 

AMC 

Matador 4V-401 A, 4,500# 

0.51 

3.8 

1.4 

10.4 


REFS 


9, 10 






15 


TABLE 4.2 


Exhaust Emission Test Summary 
California Division of Highways 
Underfloor Converter Fleet 


13 Oldsmobiles (No air pumps) 


Average Test 
Mileage 

No. of 
Cars 

194 

13 

4108 

13 

8222 

13 

12296 

5 

16022 

13 

20535 

5 

24976 

3 

24950 2 

12 

29635 

2 

12 (AIR) 

Average Test 

No. of 

Mileage 

Cars 

230 

12 

4426 

12 

8820 

12 

13857 

12 


1975 

EPA Grams/Mile^ 

HC 

CO 

N0 X 

0.19 

1.90 

1.75 

0.20 

2.22 

1.86 

0.24 

2.14 

1.84 

0.25 

2.83 

1.75 

0.24 

2.87 

1.79 

0.23 

2.13 

1.72 

0.21 

3.16 

1.93 

0.23 

2.12 

1.86 

0.19 

2.23 

2.20 


Oldsmobiles 


1975 

2 

EPA Grams/Mile 

HC 

CO 

NO 

X 

0.30 

0.91 

1.48 

0.31 

0.98 

1.62 

0.31 

1.21 

1.72 

0.35 

1.50 

1.58 


NOTES: 1 Certification test procedure 

2 

Slave canister procedure, GM reports that 1 g/mi CO 
should be added to CO levels due to variations in 
test procedures 


REF. 11 












16 


TABLE 4.2 (Continued) 

"In Service" Fuel Economy Summary 
California Division Of Highways 
Underfloor Converter Fleet 

13 Oldsmobiles (No Air Pumps) 

Average Fuel Economy (MPG) 10.6 

Fuel Economy Range (MPG) 10.2 * 11.0 

12 (AIR) Oldsmobiles 

Average Fuel Economy (MPG) 11.0 

Fuel Economy Range (MPG) 10.0 - 11.8 


No comparable fleets of production vehicles available 
for comparison. 



17 


Seventy to eighty percent of the unburned HC and CO of a 1975 
catalyst-equipped vehicle is given off during the first two minutes 
after cold start. Methods to reduce the amount of fuel used during 
choking will both lower emissions and increase fuel economy. The 
1975 emissions-control systems will use reduced choking times and 
will employ provisions for using exhaust heat for early fuel 
evaporation. Systems that have promise of effecting even better 
control during start-up include electrical heating of a charge of 
fuel, electronically operated chokes, use of a small catalyst during 
start-up that will reach operating temperature in a short time, etc. 
Further reduction in emissions is possible by increasing the quantity 
of active material in the catalyst and in some cases, by increasing 
catalyst volume. 

To reduce NO levels below the 1977 level of 2.0 g/mi while 
x 

retaining control of HC and CO, increased amounts of EGR will be 
necessary. The resultant richer mixtures required to maintain flame 
speeds and driveability will lead to fuel economy penalties. The 
latter may be minimized by using greater spark advances, but this will, 
in turn, require extra control of HC. 

Except for small, low-powered cars, where NO outputs are 

X 

basically low due to the low flows required, it is doubtful whether 
a significant number of vehicles with conventional engines and 
oxidation catalysts would be able to reach levels c£ 0.41/3.4/1.5 g/mi 
without additional control measures or without excessive fuel 
economy penalties. 


5. AIR/FUEL MIXTURE PREPARATION 


5.1 Introduction 

For emissions control to 1975 levels, considerable improvement 

in mixture preparation and delivery has been achieved. To reduce 

engine emissions and also to prevent an excessive burden on the 

oxidation catalyst, reductions of variations of A/F ratio from 

cylinder to cylinder and over the driving cycle have been necessary. 

Further improvement in mixture preparation will be required to 

meet stricter standards. A closer A/F ratio control is essential for 

lower NO emissions because all known NO control methods result in 
x x 

poor driveability and fuel economy if the mixture is allowed to vary 
widely. NO catalyst technology specifically requires very high A./F 

X 

ratio control which cannot be met with good presently used carburetors. 

Another approach to minimize emissions and to maintain or 
improve economy does not involve the use of catalysts. In a warm 
engine, the optimum A/F ratio for minimizing all three pollutants is 
on the very lean side of stoichiometry; e.g., at A/F ratios larger 
than 18-20:1 as illustrated in Figure 5.1 where HC, CO, and NO 

X 

emissions are plotted against A/F ratio. With current technology 
in mixture preparation and engine design, however, very lean mixtures 
rob the engine of horsepower output and increase fuel consumption, 
shown also in Figure 5.1. Engine and mixture-preparation technology 
are under development which will extend the range of adequate fuel 
economy and power output of lean mixtures as shown by the dotted 
lines in Figure 5.1. In this section, a discussion of improved 
mixture preparation methods will be presented which will be required 
for advanced emissions-control systems on conventional engines. 

Included will be advanced design carburetors, fuel injection and 
feedback control systems. Later sections of this report will deal 
with the emissions and fuel economy potential of lean engines and 
NO^ catalytic systems. 


18 



19 



AiR/FUEL RATIO 

FIGURE 5.1 The Relationship of Typical Engine Emissions and 
Performance to Air/Fuel Ratio. The Vertical Scale is Linear 
and Shows Relative Rather than Absolute Values for Each Param¬ 
eter . 














20 


5.2 Carburetors 

a. Conventional carburetion -- The amount of fuel issuing from 
the jet situated in a Venturi of a carburetor increases at a faster 
rate than that corresponding to an increase in air intake. The 
mixture formed by a simple carburetor thus becomes richer as the 
engine aspirates more air and, consequently, a mixture which is 
correctly proportional for high air (full load) will be too lean at 
lower air flows (idle and part load). Figure 5.2 illustrates the A/F 
ratio control of such a simple carburetor as a function of Venturi 
vacuum (or the equivalent parameter engine rpm at part load). 

An engine equipped with such a carburetor will run too rich 
at medium to full-load operation if excessive leaning out at idle is 
to be avoided, and for this reason such an engine would be highly 
polluting and poor in fuel consumption. 

Modern carburetors achieve better A/F ratio control over the 
full speed/load range by using idling and full-load Venturis, idle 
speed and transition orifices to supply additional fuel at idle, 
acceleration pump, etc. 

Figure 5.3 illustrates a cross section of a Weber 
multijet carburetor.^ 

A typical calibration curve which is conventionally used to 

provide for the mixture needs of an engine operating under all 

speed-load conditions is illustrated in Figure 5.4 for a single-barrel 

carburetor as used on the Vega 4-cylinder engine and with a carburetor 

13 

used on Chevy 6's in the 1960's (dotted line). The throttle is 
gradually opened from A(a) to D(d) and held wide open from D(d) to 
E(e) and F(f). As the engine slows down the D-E-F line the A/F 
ratio leans out because less air is being pulled through the 
carburetor. The engine comes to a lugging stall at point F. 




lb AIR/s per in^ OF THROAT AT 60 


21 



LXJ 

o 


cr 

O 

.c 

o 

c 

IT) 

CD 

O 

O 


D 

LL 

-Q 


FIGURE 5.2 





22 



FIGURE 5.3 Idle Speed Circuit 


Gam - Idle Speed Air Jet 
Gm - Idle Speed Fuel Jet 
G - Main Fuel Jet 

1 - Idle Speed Mixture Orifice 

2 - Transition or Progression Orifice 

3 - Idle Mixture Adjusting Screw 

4 - Throttle Setting or Idle Speed Adjusting Screw 


Source: Reference 12 




































Lean AlR/FUEL RATIO Rich 


23 



FIGURE 5.4 


Source: Reference 13 





24 


Pre-emission-control carburetors were able to reproduce 
the A/F calibration curve within a band of + 5 % to 107>; present 
carburetors have narrowed the band to+37 0 . These figures are, 
however, deceptive because they do not reflect the dynamic A/F ratio 
changes which occur during acceleration, deceleration modes, changes 
in altitude, air and fuel temperatures, air humidity, etc., which all 
affect A/F ratio control. 

A more serious problem with conventional carburetors is the 
variation in A/F ratio distribution from one cylinder to another 
cylinder. This problem arises from the fact that normal aspiration 
in a fixed Venturi carburetor results in relatively large fuel 
droplets which tend to segregate in the manifold. This segregation 
is more pronounced with cold engines, and under idle or low-load 
operation of the engine where the low air velocity through the 
Venturi results in large droplets which are difficult to distribute. 

Variations as large as 20% in the cylinder-to-cylinder A/F 

ratio distribution have been reported for some European and American 

14 15 

engines (see Figure 5.5). * The resulting emissions are high 

in HC and CO and can lead to premature catalyst failures. Improved 
carburetor manifold designs have reduced the A/F ratio spread to 
about 57o. 

The cost of the more complex carburetors has been increasing. 
A simple single-barrel carburetor costs approximately $5 to $10; the 
more complex multibarrel carburetors, with altitude compensation 
and other ancillary controls, may cost as much as $40. The fuel 
economy and emissions control which can be realized with these 
carburetors are marginal when compared with new mixture preparation 
devices, and it is reasonable to assume that the conventional 
carburetor will be gradually phased out by other devices in the 
foreseeable future. 


25 



FIGURE 5.5 Air/Fuel Ratio 
Distribution in an 8-Cylinder 
Engine. 


Source: References 14, 15 







26 


b. Variable Venturi carburetors and constant depression 
carburetors -- Variable Venturi and constant-depression carburetors 
overcome the problems of low air velocities which were described in 
the previous section by varying the area of the Venturi in accordance 
with the weight of air that is required per unit time by the engine. 
The Venturi can thus provide depressions and air velocities which are 
adequate to cause fuel to flow and be dispersed under most operating 
conditions of the engine. These carburetors also feature a variable 
area fuel orifice that varies with the changes in area of the Venturi 

in such a manner that the desired A/F ratio is provided at all times. 

16 

Figure 5.6 shows an example of such a carburetor. 

The piston valve can slide up and down in its guide and 
change the air passage or Venturi area. As the valve changes the 
area of the Venturi throat, it also moves the tapered metering pin 
in the fuel jet opening, and thus it provides a varying fuel jet 
orifice. The dash pot reduces the movement of the piston and 
prevents rapid upward movement when the throttle is operated 
rapidly. 

The low pressure or partial vacuum at the throttle end of 
the Venturi throat causes air to flow through the piston vent until 
the pressures in the vacuum chamber and Venturi throat are equal. 

The lower side of the flex diaphragm has atmospheric pressure 
acting on it, and the force due to the pressure differences lifts the 
piston up or down. 

Thus, for each air flow rate through the Venturi there is a 
corresponding position of the piston valve, and a particular value of 
the vacuum in the throat of the Venturi. The size of the fuel jet 
orifice and the taper of the metering pin are made so that the fuel 
flow with any given position of the piston valve is the desired flow. 

Most carburetor companies are working on some version of 
the Variable Venturi (V.V.) carburetors. Most have chosen combination 




27 



FIGURE 5.6 


Source: Reference 16 











































28 


carburetors with one barrel operating with a fixed Venturi while the 
other performs as a V.V. version. This version of carburetor appears 
to have the best chance of being interfaced with electronic controls 
as will be discussed later. 

Table 5.1 summarizes some results which were achieved with 
a 1973 Dodge Monaco with a 1974 360 CID V-8 engine and the 
experimental Holley model 2880 Variable Venturi carburetor. 17 

TABLE 5.1 

A/F ratio control +37o 
HC = 1.48 g/mi 

CO = 10.28 g/mi 

NO = 1.8 g/mi 

x 

Spark timing - 60° BTC 
No air pump 
107o EGR 

Fuel Economy - 11 mpg 

A fixed Venturi 4-barrel carburetor of similar design has 

higher HC and CO emissions (approx. HC - 2.5 g/mi, CO - 20 g/mi) and 

equivalent fuel economy. NO remains unchanged. 

x 

In spite of these improvements, the Variable Venturi 
carburetor will not achieve the A/F ratio control required for the 
three-way catalyst and simultaneous control of HC, CO, and NO . 

X 

c. Sonic carburetors -- The size of droplets produced by 
a carburetor varies approximately inversely with the velocity of 
air flowing through the Venturi. Figure 5.7 shows the relationship 
between air velocity and fuel droplet diameter entering the intake 
manifold. 1 ^’ 1 ^ The droplets which are achieved at sonic velocities 
(approximately 1000 ft/sec) and above are so small that little 
segregation occurs within the carburetor and intake manifold, and. 



29 



Source: References 18, 19 




30 


consequently, sonic carburetors have much lower cylinder-to-cylinder 
A/F ratio variations than conventional carburetors. 

The Dresser carburetor is the best known sonic carburetor 
and considerable work is being performed throughout the industry 
to develop its potential. 

The Dresser carburetor or "Dresserator" is a Variable Venturi 

20 

carburetor with a mechanically actuated fuel distribution bar. The 

21 

principle is shown in Figure 5.8. 

The device shows promise of improving atomization, mixture 
quality, A/F distribution, and control. It achieves these 
improvements by: 

. Designing the entrance/exit geometry to produce sonic flow at 

the carburetor throat which results in superior fuel atomization. 

. Introducing fuel over a large surface area which is subjected to 
sonic air-flow levels. 

. Passing the A/F mixture through a shock wave to atomize the fuel 
and improve mixing. 

. Eliminating flow distortion caused by downstream throttle plates. 

. Coupling the throttle with a linear fuel-control valve to achieve 
constant A/F control. 

. Eliminating the choke, although some enrichment is necessary 
during start-up. 

The mixture quality which can be achieved with sonic 

carburetors is compared with conventional production carburetors, EFI, 

stratified-charge engines (PROCO) and liquid propane (LPG) or liquid 

natural (LNG) cars in Figures 5.9 and 5.10 for various points in the 

22 

induction system. 


31 



Source: Reference 21 












32 



FIGURE 5.9 Ford Motor Company Estimate of Induction System 
Mixture Quality Trends Under Hot Operating Conditions. 


Source: Reference 22 





33 



FIGURE 5.10 Ford Motor Company Estimate 
of Induction System Mixture Quality Trends 
Under Cold Start and Drive Conditions. 


Source: Reference 22 













































































34 


With exception of LNG and LPG, sonic carburetion provides the 
most homogeneous mixtures and thus improved distribution. 

Sonic carburetion is still in the development stage and a 
variety of problems remain to be resolved among them: 

. Actuation forces under sonic conditions are high and lead to 
rapid component wear, 

. Need for altitude and temperature compensation, 

. Manufacturability and durability, 

. Cold start where sonic velocities cannot be achieved. 

d. Hot-spot carburetors -- As was shown in Figures 5.9 and 5.10, 
LNG and LPG produce better mixtures than gasoline because they evaporate 
more readily than gasoline in the operating temperature range of the 
engine. Similarly, cylinder-to-cyUnder A/F ratio variation could be 
eliminated by vaporizing and mixing the gaseous gasoline with the 
incoming air. Several difficulties are associated with this 
approach are: 

. The heat required to vaporize all fuel under full-load conditions 
is over 2KW and cannot be supplied by the automotive electric 
power. 

. The fuel evaporator has to be designed to prevent simultaneous 

heating of the incoming air and associated volumetric efficiency 
losses. 

. Vapor lock has to be prevented. 

None of the fuel evaporation systems which are presently under 
evalutation has resolved these problems satisfactorily. 

Most automobile manufacturers use hot spots or early fuel 
evaporation (EFE) devices to help daring cold start. These are 
turned off as soon as the engine reaches operating temperature and 



35 


therefore do not influence the cylinder-to-cylinder A/F ratio 
distribution of the warm engine. 

The Ethyl Corporation, Shell Laboratories in England, and 

? 3 a# 5 

British Leyland - * ’ are experimenting with evaporative heaters 

which are kept in operation during the full operating range of the 
engine. The objective of these approaches is to improve the A/F 
ratio distribution to allow ultralean operation of the engine under 
all load conditions. 

The Ethyl Corporation's hot-box manifold is shown in 
Figure 5.11. 

The hot box is situated underneath the primary barrels of 
a Quadrajet carburetor and sunk into the exhaust manifold crossover. 
The fuel/air mixture of the primary barrel passes through the hot 
box under all driving conditions; the air/fuel mixture of the 
secondary barrel, on the other hand, bypasses the hot box under 
all conditions. 

Since the air-flow velocities of the secondary barrel 

provide for good fuel distribution without evaporation, the resulting 

A/F distribution is better under all driving loads. The main flow 

of air is not heated by this system and, therefore, the volumetric 

efficiency is maintained. The cylinder-to-cylinder variation of 

this carburetor mounted on a 350 CID Plymouth engine is shown in 
23 

Table 5.2. 

The A/F ratio spread with this carburetor is approximately 
3% under idle and 1.6% at 30 mph. This is an improvement of a factor 
of 2 over a conventional carburetor. Further improvement are 
anticipated from a variable Venturi arrangement in the secondary 
barrel. 




36 


Secondary 




FIGURE 5.11 Ethyl Corporation’s Rectangular Hot 
Box Manifold for a 360 CID Plymouth. 


Source: Reference 23 


























































37 

TABLE 5.2 


Cylinder-To-Cylinder Distribution Spreads 


Cruise A Distribution 


Speed 

A/F 1 

F/A 2 

A A/F 

A F/A 

Idle 

16.3 

.061 

0.50 

.0020 

15 

17.5 

.057 

0.49 

.0016 

30 

17.3 

.058 

0.28 

.0009 

50 

16.6 

.060 

0.47 

.0016 


^A/F = air/fuel ratio 
? 

F/A = fuel/air ratio 





38 


Typical emissions results for a modified* 1974 Dodge 4,500 lb 
360 CID engine are (g/mi): 


HC -- 

1.33, 

can 

be 

improved 

to 

CSl 

• 

T—H 

r-H 

• 

t-H 

CO -- 

7.80, 

can 

be 

improved 

to 

6-7 

NO -- 

X 

2.76, 

can 

be 

improved 

to 

2.3-2.5 


Fuel economy -- 10.7, can be improved to 11.2 mpg 


Base-line figures for the conventional Quadrajet carburetor 


(g/mi): 


HC -- 

2.8 

CO -- 

26.0 

NO -- 

2.5-2.7 


x 

Fuel economy -- 11.0 

The Shell Laboratories' (England) Vapipe approach is to use 

the exhaust heat to heat and evaporate all the fuel under all engine 

24 

operating conditions. Heat is transferred to the carburetor with 
heat pipes which are connected to the exhaust manifold (see Figure 5.12) 
The results are similar to those achieved by Ethyl Corporation 

The engine can be operated at very lean A/F ratios without losing 
driveability. 

. The A/F cylinder-to-cylinder distribution is excellent (Table 5.3) 


*Equipment: Carter Thermo-Quad Carburetor 

Electric choke assist 
Ethyl hot-box manifold 

EGR -- control with Venturi and throttle position sensor 
Timing 5° BTC 




39 



Source: Reference 24 










































COMPARISON OF AIR-FUEL RATIO DISTRIBUTION 
WITH AND WITHOUT VAPIPE -1.8 LITRE (110 CU.IN.) CAR 


40 



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41 


. The emissions of all three pollutants are lowered. 

. Fuel economy is improved over that of the same engine with a 

conventional carburetor. 

e. Carburetor with ultrasonic fuel dispersion -- Recently 
several carburetor-like devices have been proposed which use 
ultrasonic energy to achieve good fuel dispersion and cylinder-to- 
cylinder mixture distribution. One version is being developed by 

Autotronics. Another version, which has been proposed by Dr. A. K. 

26 

Thatcher and Dr. Ed McCarter, Florida Technical University,“ uses 
a magnetostrictive transducer at frequencies of 20,000 to 40,000 
Hz to break up the fuel stream into very small droplets. The device 
is shown in Figure 5.13. Fuel injectors spray fuel onto the surface 
of the horn of a magnetostrictive transducer where the fuel is 
atomized into very small droplets which are mixed with the flowing 
air. The device was evaluated on a Plymouth Duster with a 225 CID 
slant six engine and is summarized in Table 5.4. 


TABLE 5.4 


Duster with 

Duster with 

Ultrasonic Device 

Std. Carburetor 

(g/mi) 

(base-line) (g/mi 

HC - 0.44 

4.9 

CO - 0.88 

6.6 

NO - 1.0 + 30% 
x ~ 

3.0 to 8.0 

MPG - 22 

18 


The base-line HC and NO emissions seem overstated; however 

x 

the improvements in emissions levels with this system are believable 
The large difference in fuel economy cannot be justified by what is 



42 



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43 


known about the device alone. The drawbacks of the system, as 
presently implemented, are high power consumption, noise, complexity, 
and thus, high cost. Therefore, it seems that the objective of 
better fuel dispersion may be accomplish more easily with a sonic 
or hot-spot carburetor or fuel injection. 

5.3 Fuel Injection Systems 

a. Electronic fuel injection - speed and density systems -- The 
oldest electronic fuel injection system (invented by the Bendix 
Corporation approximately 15 years ago and perfected and manufactured 
by Robert Bosch, Germany) measures air density and engine speed to 
derive the air quantity drawn in by the engine and to inject the 
appropriate amount of fuel. 

Robert Bosch started production of this system in 1967 and 

has presently 1.5 million of the D-jetronic EFI types in the field 

installed on 40 different 4-, 6-, and 8-cylinder engines. The 

27 28 

principle of the system is illustrated in Figure 5.14. ’ 

The air quantity drawn in by the engine is determined by 

measuring the engine rpm and electronically multiplying this figure 

by the engine displacement constant. A manifold vacuum pressure 

transducer and an ambient air temperature sensor convert the air 

volume to standard temperature and pressure (STP). The electronic 

control logic processes these signals and injects the appropriate 

amount of fuel into the intake manifold through fuel injectors which 

are positioned on top of the cylinder heads. Fuel is fed to these 

injectors through a well-regulated, pressurized fuel rail. 

The D-jetronic system is a pulsed injection system where the 

quantity of fuel is modulated by changing the length of the injection 

pulse. The D-jetronic system sells to the original equipment market 

29 

(OEM) in Europe for approximately $120 for a 4-cylinder version. 

For this reason, it has found only limited application in spite 





44 


Injector 


Manifold 

Density 



Air Flow 


Air Flow (Ib/min) = 
Displacement (l 3 /rev) X 
Speed (rev/min) X 
Cylinder or 
Manifold Density 
(Ib/1 3 ) 



FIGURE 5.14 


Source: References 27, 28 






























































45 


of the fact that it has been offered in Europe for over seven years. 

The Bendix Corporation in the United States has developed a similar 

speed density system but has failed to find wide acceptance again, 

27 

mainly due to the high cost of the system. 

There is considerable controversy about the benefits of 
electronic speed density fuel injection systems: 

. It is well established that the maximum power output for a given 

engine can be improved; for example, with electronic fuel 

injection (EFI), a 2.8 liter Daimler Benz gasoline engine 

delivers 185 hp at wideopen throttle (WOT) and only 150 hp with 
30 

a carburetor. This advantage is due to the better volumetric 
efficiency and full power enrichment with EFI. (The EFI 
manifold has fewer obstructions for the inrushing air.) This 
advantage is mainly realized at full throttle, particularly 
with high speed European engines - most current U.S. cars 
rarely operate at full load and would not benefit from EFI. 

. Electronic fuel injection can offer better cylinder-to-cylinder 

A/F ratio distribution for poorly designed engine manifolds 

and engine types which have difficult induction problems. An 

example is the air cooled opposed piston engine used by 
14 

Volkswagen. This engine has long intake manifolds and a 
cylinder firing sequence which makes it difficult for some 
cylinders to get the correct charge. Traditionally, this engine 
was carbureted rich in order to assure that all cylinders had 
adequate mixtures. The consequences were high emissions. 
Electronic fuel injection solved the problem by supplying 
each cylinder with the appropriate amount of fuel. Electronic 
fuel injection, in itself, does not have any advantage over a 
well carbureted engine. For example: 



46 


Saab 2 Liter Engine 3,000 lb. 

Automobile 

31 


(Raw Engine Emissions) 

HC 

CO 

N0 X 

MPG 

D-jetronic 

(dual catalyst) 1.18 

40.9 

2.19 

16 

Carburetor 

(dual catalyst) 1.9 

40.7 

2.4 

17.7 

Close loop K-jetronic 

(3-way catalyst) 0.9 

8.14 

2.2 

19.3 

Electronic fuel injection improves cold- 

start performance. 

again, 


particularly for European engines with simple carburetors and 
choke systems. U.S. cars do not benefit from this feature. 

Some European manufacturers have opted to use EFI rather than 


to design an advanced carburetor because it was cheaper to do so. 

In summary, D-jetronic EFI can offer some advantages in A/F 
ratio distribution for a few engines with difficult manifold and 
firing sequence problems. It improves cold start and power output 
at WOT. It does not offer fuel economy and emission advantages over 
well carbureted engines. 

b. Electronic fuel injection - air mass system (L-jetronic)-- 

In 1972 Robert Bosch produced the L-jetronic system, a second 

generation EFI, which monitors the quantity of air drawn in by the 

engine directly with an air mass sensor as shown in Figure 5.15. This 

32-34 

system has been described in several publications. The air 

mass is measured by a flap situated in the main air stream. The 
force of the flowing air on the flap is balanced against the force 
of a return spring. To eliminate rapid pulsation, the device 
incorporates an air chamber and another flap which acts as a dash 
pot damper (stabilizer volume). A butterfly valve in the air flow 
measuring flap absorbs backfiring pulses. The flap angle is converted 
into voltage by the potentiometer which is attached to the axis of 
the flaps. This device eliminates the pressure and temperature 





Throttle Valve-Engine 


47 


FIGURE 5.15 



Source: References 32, 33, 34 


















































48 


sensors of the D-jetronic system and simplifies the electronic 
circuit. 

The rest of the L-jetronic system is similar to the D-jetronic 
system. It has a pressure regulated fuel rail, port injection, an 
additional injector for cold start, etc. The L-jetronic system, 
however, offers the following improvements: 

. Improved start-up which leans out the engine faster. 

. Deceleration control. 

. Simultaneous injection of all injectors (rather than sequential) 
which allows the injection pulse length to increase and to reduce 
the injection time error. For example, at full load, the 
injection pulse is 8 msec with the L-jetronic and 4 msec with the 
D-jetronic EFI. Since the pulse rise time is 1.6 msec, the 
errors introduced at a 4-msec pulse width are considerable. 

The L-jetronic EFI is more rugged and measures air more 
accurately. For example, the air-mass meter is independent of 
barometric and back pressure changes which throw off the calibration 
of the D-jetronic system, and it monitors air flow independent of 
EGR. 

The L-jetronic system is approximately 10% cheaper than 
the D-jetronic system, viz., approximately $110 for a 4-cylinder 
European engine versus approximately $120 for the equivalent 
D-jetronic system. Because of these advantages, most users of 
D-jetronic EFI, particularly Volkswagen, will switch in 1975 to 
L-jetronic EFI. 

The raw emissions of the L-jetronic system are lower than 

those achieved with D-jetronic EFI; 1975 Federal standards can be 

met comfortably. For example, a 1.6 liter air-cooled Volkswagen 

, 35 

engine measured: 


49 


HC - 1.16 g/mi 
CO - 7.1 g/mi 
NO r - 1.22 g/mi 

The L-jetronic system does not seem to offer significant 

35 

fuel economy advantages. Volkswagen reports, for example 18.3 miles 
per gallon in 1974 vs. 17.8 miles per gallon in 1975 for their Type 2 
air cooled engine. Other models show slight increases in 1975. 

In summary, the L-jetronic system reduces emissions when 
compared to the D-jetronic system. These improvements are due to 
better air measuring inputs, improvements in the start-up, 
deceleration controls, and injection timing. The L-jetronic system 
is capable of meeting the 1975 federal standard but cannot meet 1975 
California standards without oxidation catalysts or thermal reactors. 
Fuel economy remains equivalent to D-jetronic or well carbureted 
engines. 

c. Mechanical fuel injection (K-jetronic system) -- The 
36 37 

K-jetronic system ’ uses the intake air volume as the controlling 
variable to determine the A/F ratio and to eliminate the need for 
electromechanical conversion. Figure 5.16 shows the schematic of 
the system. 

The floating flap air-sensor plate is mounted on a lever 
having a balanced weight attached to the short end. The flow rate 
of intake airlifts the plate until an equilibrium is reached 
between air flow and hydraulic counter pressure which acts on the 
lever through a controlled piston. In this balanced position, the 
plunger maintains a certain position in the fuel distributor, thus 
opening small metering slits, one for each engine cylinder. The fuel 
supplied by a pressurized fuel rail system passes through the slit 
openings to the injection valves. The correct amount of fuel is 
provided by the slit openings, than in the injection valve as in 



50 



FIGURE 5.16 


Source: References 36, 37 




















































































51 


electronic fuel injection. 

Hydraulic counter pressure acts on the top of the control 
piston to influence the fuel quantity needed by the various operating 
conditions of the engine. By exerting more force on the top, the 
plunger travels less, and less fuel flows to the injection valve. 

The opposite is true when the pressure is released. The control 
pressure is varied by control-pressure regulators, one regulating 
according to engine and outside temperature and the other according 
to accelerator pedal position. The controlled pressure regulator for 
temperature compensation maintains the correct A/F ratio by enriching 
the mixture during engine warm-up. As the engine reaches its normal 
running temperature, it leans out the mixture. This control-pressure 
regulator contains a bimetal spring which acts on a spring-loaded 
diaphragm (see Figure 5.17). For example when the engine is cold, 
the diaphragm keeps the inlet open to maintain a minimum pressure 
on the plunger of approximately 2.3 atm. As the heating coil of 
the bimetal spring heats up, it permits the diaphragm to close off 
the inlet opening, thus increasing the control pressure and leaning 
out the mixture. 

The control-pressure regulator for throttle vavle position 
compensation is mounted on the throttle valve shift (see Figure 5,17). 
According to accelerator movement, the control pressure on top of 
the plunger is again changed to provide the correct A/F ratio. When 
the throttle is at idle, the control pressure is maintained at 3 atm. 
at mid-range throttle opening, 3.7; and at wide open throttle, 2.9; 
thus increasing fuel delivery as the throttle is depressed. 

The K-jetronic system has a starting valve which provides 
additional fuel during start-up conditions, and has a number of 
significant advantages over both electronic fuel injection systems: 


52 


To 

Tank 


I 




7. Control pressure regulator for 
warm-running compensation. 
A-cold position; B—warm position. 


f 

2.9-3.1 To ^ (j _3 q To 




8. Control pressure regulator for throttle valve position compensation. 
A—idle position; B—midrange position; C—full-throttle position. 


t * 





1 

J1 



% urn /[f 








9. Fuel accumulator prevents vapor 
locking of the system. 



10. Auxiliary air device assures good 
air-fuel ratio during deceleration. 


FIGURE 5.17 


Source: References 36, 


37 


































































































































































53 


It is a simpler system and is understood by mechanics. 

It is lower in cost. The OEM cost for the system in small 
quantities is approximately $100 and is likely to be lowered as 
the volume production commences. 

The K-jetronic system is s'lightly better than the L-jetronic 
system in controlling emissions and improving fuel economy 
because it minimizes time lags associated with sensor signals 
and fuel-injection pulses. 

The K-jetronic system is capable of meeting the 1975 federal 
standards, but it cannot meet the 1975 California standards 
without a catalyst. 

• In summary: The K-jetronic system provides the same advantages 
over carburetors as the other two electronic fuel-injection 
systems; namely, higher power output under wide open throttle 
conditions, less air induction problems and better cold start. 

The fuel economy is approximately the same as with the L-jetronic 

system, although Audi, Volvo, and Saab claim some minor 

advantages. Volvo claimed that the fuel economy of their two- 

liter, carbureted engine increased from 17 mpg to 19 mpg for 

38 

the same engine with a K-jetronic fuel-injection system. 

39 

Saab, on the other hand, showed an example during the 
Washington presentations of a carbureted engine with better fuel 
economy than one with K-jetronic injection. 

This difference in opinion illustrates the danger of 
extrapolating the emission and fuel economy results achieved 
with one type of intake-manifold-engine combination as compared 
to another even if the same carburetor or fuel-injection system 
is used in both. 


54 


. The emissions from K-jetronic injection are equivalent to those 
of the L-jetronic system. 

5.4 Feedback Systems 

The A/F ratio of an operating engine is influenced by the 
temperature of the air, temperature of the fuel, the humidity of 
the air, the chemistry of the fuel which affects density surface 
tension and viscosity, the absolute pressure of the air, the back 
pressure of the engine and the shifts in calibration of fuel 
metering rods, orifices, etc. Of all these variables, only a few are 
monitored with present fuel-metering devices: 

. The advanced carburetor will have altitude compensation but has 
no sensors for air temperature, humidity, etc. 

. The electronic and mechanical fuel-injection systems will also 

incorporate altitude compensation and air temperature measurements 
but do not monitor variables such as humidity, fuel viscosity, 
etc. 

For these reasons, open-loop fuel metering cannot be correct under 
all conditions of vehicle operation. Only a closed-loop system which 
monitors either the composition of the exhaust gases or some engine 
output parameter, such as horsepower output, can maintain the A/F 
ratio within correct limits by constantly supplying corrective 
signals to the primary F/A metering device. 

Two main approaches are being pursued at the present time: 

. Systems based on the exhaust-gas composition, specifically, 
systems monitoring the oxygen content of the exhaust system; 

. Systems based on engine output parameters, particularly horsepower 
output. 



55 


a. Feedback systems based on the 02 - exhaust gas sensor and 

EFI, mechanical (continuous) fuel injection or electronic 

carburetors -- In 1971, Robert Bosch proposed a new exhaust-gas 

composition sensor which provides a strong variable voltage signal 

40 

around the stoichiometric composition of the A/F mixture. The 
sensor output was used to close the feedback loop with the L-jetronic 
electronic control unit and to correct the fuel injection pulses and 
maintain the A/F ratio at exact stoichiometric composition. The 
control achieved with this feedback was typically an order of 
magnitude better than that achieved with advance carburetors or 
approximately +0.37 o vs the +3% achieved with the best carburetor 
system. 

The heart of this control system is the oxygen sensor. Such 
a sensor is shown in Figure 5.18. It consists of a doped ZrO^ tube 
with phatinum electrode on each side. One side of the sensor is 
exposed to the exhaust manifold gases, the other to the atmosphere. 
The sensor operates as an electrochemical oxygen concentration cell 
with Zr0 ? solid electrolyte. The platinum electrode acts as a 
reaction site for the reaction: 


CO 

+ 

0 

CM 

o 

o 

and 

HC 

+ 

0 

h 2 ° 

+ CO 


and the sensor output is determined by the oxygen partial pressure 
of these reactions or the concentration of oxygen on the surface 
of the senor rather that the "free" oxygen concentration in the 
exhaust stream. 

As the mixture goes from rich to lean, the partial pressure 

12 

of oxygen on the surface will change by a factor of 10 or more and, 
according to the Nernst equation, a step-like voltage change of 
almost one volt will appear across the electrodes of the sensor as 





56 



FIGURE 5.18 

Source: Reference 40 


Pq 2 (exhaust) 





























57 


shown in Figure 5.19. A signal will always occur at stoichiometric 
exhaust gas compositions regardless of temperature or exhaust gas 
flow rate. The rise time of the signal is very rapid (milliseconds). 
The sensor has to be brought to at least 400°C before a useful 
signal appears and the output is temperature dependent as in Figure 
5.20. By choosing the control point at 500 mV or below, the 
temperature sensitivity can be eliminated because temperature 
changes occur mainly at the rich end of the output. 

The problems which plagued the oxygen sensor a year ago 
thermal cracking, aging, and seal leaks, have been virtually 
eliminated, and Bosch in Germany and UOP in the U.S. claim to have 
sensors which can be guaranteed for 12,000 miles or more. The 
evidence submitted to support these claims was convincing. 

The oxygen sensor feedback loop can be used in conjunction 
with the L-jetronic EFI, the K-jetronic mechanical injection system 
or electronic carburetors. The cost of feedback-control systems may 
decrease rapidly because they may eliminate many presently used 
ancillary control such as fast chokes, altitude compensation, air 
pumps, EGR, etc. The feedback control is very exciting new technology 
with great potential to achieve low emissions with low fuel 
consumption and control system cost. 

b. Feedback system based on engine output sensors -- Dr. P. 

42 

Schweitzer has proposed to use an engine feedback signal to vary 
the mixture ratio of the engine under all driving conditions. The 
principle of the control or "Optimizer" system is illustrated in 
Figure 5.21. 

In this version of the control system, the intake manifold 
system is provided with an auxiliary air intake passage. A dither 
plate continuously oscillates to change the air intake within narrow 
limits. As the mixture composition changes, the engine speed 
fluctuates within narrow, but well-defined limits. These variations 



58 



X 

FIGURE 5.19 Sensor Characteristic. 


Source: Reference 40 





59 



(AW) IDdlDO U0SN3S 








60 



To Engine 

FIGURE 5.21 Optimizer Control. 


Source: Reference 42 






















61 


in engine speed are monitored by a deceleration/acceleration sensor 
(the Celsig, the derivative of rpm information) and fed into the 
control logic. The control logic adjusts the main air intake to the 
engine in such a way that the change maximizes engine rpm. In this 
fashion, this control optimizes horsepower output of the engine under 
any driving condition and thus minimizes fuel consumption. 

Dr. Schweitzer has made preliminary calculations of the 
system and claims lower emissions with improved fuel economy, but the 
system has not been tested on a car. 

The optimizer control is probably useful for minimizing fuel 
consumption irrespective of engine emissions. Used in conjunction 
with a normally tuned carburetor, operating around stoichiometry, 
the ^missions would probably be high because the optimizer control 
would tend to operate at the maximum power point which occurs at the 
rich side of stoichiometric. 

The optimizer control may have more merit in conjunction 

with advanced carburetor or fuel-injection systems which maximize 

the power output on the lean side of stoichiometric. In this 

case, good fuel economy may be coupled with low hydrocarbon and carbon 

monoxide emissions. An example would be a combination of optimizer 

control with a sonic or hot-spot carburetor. It seems, however, 

mutually exclusive to optimize fuel economy and minimize NO with this 

x 

method. Therefore, the usefulness of this feedback control will be 

small to achieve NO emissions below 2 g/mi. 

x 


6. LEAN BURN SYSTEMS 


Maximum rates of NO^ formation occur at F/A equivalence 
ratios about 0.9 (fuel lean), Figure 5.1. Significant reduction in 
NO can be obtained by operating much leaner than this. Further, at 

X 

lean mixtures, excess oxygen available provides for complete 
combustion of CO and HC and potentially low levels of these pollutants 
in the exhaust gas stream. Advantages in fuel economy can be 
realized by running lean, as long as means are taken to ensure 
complete combustion of the charge. At very lean A/F, as shown in 
Figure 5.1, HC levels start to increase as the quench zones become 
thicker and misfire is approached. Further, systems that use lean 
mixtures are generally limited by an exhaust temperature which can 
lead to high HC emissions. Retarding timing and reducing the 
compression ratio to achieve higher exhaust temperature and lower 
HC emissions leads to fuel economy penalties. 

Conventional carburetors and induction systems are not 
adequate to maintain reliable operation at mixture ratios of 17:1 and 
leaner. It is especially important for lean operation to have a 
homogeneous mixture delivered to each cylinder at the same A/F ratio. 
Techniques to achieve such mixtures have been described in Section 5; 
namely, the Ethyl system, Shell Vapipe and Dresser carburetor. 

Results from the Ethyl system, featuring a hot-box manifold, 
were presented on pages 33,36 and 37. When this system was modified 
to include an exhaust lean thermal reactor, with overall system A/F 
ratio 17:1, emission levels in Table 6.1 were achieved. 

43 

Table 6.1 

1974 Dodge, 360 CID, 4500 lb (Ethyl tests) 

With reactor 
HC 
CO 
N0 X 


62 


0.55 

5.0 

1.40 



63 


Fuel economy, as measured on a cold-start 1972 test procedure, was 

10% to 15% better than that of the base vehicle. 

The Shell Vapipe system is designed for very lean operation 

with homogeneity achieved by fuel vaporization. Data have been 

obtained on a 1.8 liter Morris Marina of 2,500 lb inertia weight with 

manual transmission. This vehicle is made for the European market 

so has no EGR, and very little in the way of emissions controls except 

for the Vapipe. Results of the average of 6 tests on the 1975 FTP 
44 

are 


HC 

4.9 g/mi 

CO 

5.9 g/mi 

NO 

1.5 g/mi 

X 

MPG 

22.6 MPG 

A/F 

16.5 to 1 


Improvement in fuel economy has been achieved out to A/F ratio of 
20:1 although at these very lean ratios, two spark plugs are 
necessary, with as much as 80° advance. A problem that must be 
overcome with this system is the time required to bring the heat pipe 
into operation (2 minutes). 

The most promising system for obtaining the advantages of 
lean operation through improved carburetion appears at present to 
be the Dresserator. The Dresserator carburetor is a variable-throat, 
supersonic nozzle, operating choked for manifold vacuum of less than 
3 inches of mercury. Cold start is possible at A/F ratios of 17.5:1 
without the use of a choke. A/F ratios of 20:1 can be used without 
operational difficulties. Results with the Dresserator on the 1975 
FTP are shown in Table 6.2. 

Dresser claims 60% reductions in HC with the use of an enlarged 
exhaust manifold, presumably resulting in increased exhaust reactions. 


64 


TABLE 6.2 


A. 


1971 Ford Galaxie, 4,500 lb.. 


9:1 CR, 


351 CID 


45 


(Tests at Dresser) 


Baseline 


HC 

CO 


2-3 

40 


g/mi 

g/mi 


With Dresserator & Enlarged 
Exhaust Manifold 


NO 

4-5 g/mi 

HC 

0.3 

g/mi 

X 

MPG 

10.5 

CO 

4-5 

g/mi 



NO 

X 

1.2 - 1.7 

g/mi 



MPG 

11 



With Dresserator 

HC 

0.8 - 1 g/mi 

at A/F 18:1 

No Vacuum Advance 

CO 

6-8 g/mi 


NO 

X 

1 - 1.5 g/mi 


MPG 

11 

B. 1973 Chevrolet 

Monte 

Carlo, 4,500 lb., 

(Tests 

at GM) 

(Conventiona 


HC 

0.849 g/mi 


CO 

3.95 g/mi 


NO 

X 

1.915 g/mi 


MPG 

11.51 


46 


47 

C. Results from EPA (75 FTP) 


1973-,. 2600cc, 

Vu 

HC 

CO 

N0 X 

MPG 

r 

Ford Capri, retarded timing 

0.68 

5.8 

1.21 

18.2 

Chevrolet Monte Carlo, retarded timing 
as above 

1.11 

5.1 

1.56 

12.8 


REFS. 45, 46, 47 





65 


Ford currently has an extensive program underway to develop 
the Dresser type carburetor. Results at Ford with a 4,500 lb 

48 

inertia-weight Galaxie, 351 CID, no EGR, indicate the following: 

HC 0.70 g/mi 

CO 4.17 g/mi 

NO 1.93 g/mi 

x 

MPG 10.7 

(Results on 75 FTP) 

In general terms, these results are consistent with those of GM, 

EPA and Dresser. 

The versions of the Dresser carburetor used to obtain the 
dat^ quoted above are mostly research tools, and not suitable for 
production. Many significant problem areas remain, including 
difficulties in precisely controlling the throat area with the 
large forces involved, wear of linkages and cams, correct location of 
fuel intake, and operation during unchoked conditions (wide-open 
throttle). Ford is working on three versions of the sonic carburetor, 
one with annular throat and two with rectangular throat. Several 
years of development effort are needed before this carburetor can be 
considered ready for large-scale production. 

Nevertheless, the Dresserator system, without catalyst or EGR, 
can meet California 1975 standards, and, possibly with the addition 
of an exhaust thermal reactor and improved inlet manifold, meet 
levels of 0.41/3.4/2.0. Fuel economy at these emission levels should 
be equivalent to that of a 1975, 49-state model car. 


7. DUAL CATALYST SYSTEMS 


To reach levels of NO below 1.5 g/mi while retaining the basic 

x 

components of the 1975 catalytic system will require the use of a 
reduction catalyst. The typical system will consist of a NO catalyst 

X 

located near the engine exhaust manifold, an oxidation catalyst down¬ 
stream, with air injection prior to the oxidation catalyst. Carburetion 
must be rich to provide a reducing atmosphere for the NO catalyst. 

X 

In such systems, during the start-up phase, air is injected upstream 

of the NO catalyst, with the reduction bed acting as an oxidation 
x 

catalyst during the start-up period. 

F/A ratio must be carefully controlled for satisfactory operation 
of the NO catalyst. Too great an input of CO to the bed will lead to 

X 

excessive formation of ammonia; too small a concentration of CO will not 

provide the correct reducing atmosphere required. Further, it is 

desirable to avoid lean transients when the catalyst is up to 

temperature, which may lead to excessive temperatures on the reduction 

bed and, at least for some catalysts, cause failure. 

Several techniques have been used to control the ratio of CO to 

0^ in the inlet gas stream to the reduction catalyst. Certainly, 

one way is the use of improved carburetors which much enable control 

of F/A to within 6% over the operating regimes of the vehicle. This 

has generally been the approach of the auto manufacturers, with results 

using noble-metal catalysts as shown in Table 7.1 below. 

An accumulation of data on performance of NO^ converters developed 

by various catalyst manufacturers and tested on General Motors vehicles 

49 

is shown in Figure 7.1 Even the most attractive catalyst from this 
chart, curve L, was over the CO standard after 8,000 miles (Figure 
7 . 2 ). More recent low-mileage data from GM on dual catalyst systems 
are shown in Table 7.2a,b. Fuel economy for the base 1975 vehicle 
is 12 mpg.50 jt can be seen that, for small cars, results on the best 
experimental vehicles indicate levels under 0.41/3.4/1.0 up to 10,000 
to 20,000 miles with fuel economy between 07, and 57> worse than 1975 


66 


67 

TABLE 7.1 


Experimental Results - Dual Catalyst System 


Manufacturer 

Mileage 

HC 

CO 

N0 X 

1 . 

Ford Galaxie, 351 CID 

0 

0.8 

2.9 

0.6 



9,000 

1.2 

6.2 

0.7 


49 





2. 

Ford Galaxie, 351 CID 

0 

0.7 

3.0 

0.7 



10,000 

0.7 

3.4 

0.8 



22,000 

1.0 

7.0 

1.0 


49 





3. 

Ford Galaxie, 400 CID 

0 

0.6 

0.9 

0.4 



8,000 

1.0 

1.5 

0.5 



12,000 

1.2 

2.0 

0.7 

4. 

General Motors, 5,000 IW 






350 CID, EGR 50 

0 

0.36 

1.9 

0.41 



3,000 

0.41 

2.4 

0.56 

5. 

General Motors, 5,000 IW, 

350 CID, EGR^ 0 

0 

0.31 

2.8 

0.24 



8,000 

0.38 

3.4 

0.24 



12,000 

0.94 

4.4 

0.38 



16,000 

0.84 

7.6 

0.34 



20,000 

0.66 

3.4 

0.36 



24,000 

0.8 

6.8 

0.36 

6 . 

British Leyland, Austin 

0 

0.39 

1.32 

0.29 


Marina^ -*■ 

6,740 

0.53 

1.71 

0.27 



10,720 

0.58 

1.7 

0.64 

7. 

British Leyland, Austin 

0 

0.15 

0.67 

0.45 


Marina^1 

10,875 

0.38 

1.8 

0.85 

8. 

British Leyland, Austin 






Marina^l 

0 

0.19 

2.49 

0.35 



6,600 

0.36 

1.51 

0.23 

9. 

52 

Nissan, 119 CID, Datsun 

0 

0.09 

1.08 

0.33 


2750 IW 

4,600 

0.27 

0.73 

0.39 



11,700 

0.30 

0.93 

0.48 



20,700 

0.39 

1.67 

0.68 

10. 

52 

Nissan, 119 CID, Datsun 

0 

0.21 

1.38 

0.30 


2750 IW 

11,800 

0.33 

1.1 

0.31 



18,300 

0.57 

4.07 

0.39 

11. 

53 

Toyota, 2,500 IW, 1.6 liter 

0 

0.11 

1.89 

0.43 


5,000 

0.17 

1.12 

0.49 





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69 





AMA MILEAGE IN THOUSANDS 

FIGURE 7.2 AMA Durability Test Oxidizing and Reducing Catalyst. 


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vehicles. Durability results are not as encouraging for large cars 
with higher engine NO emissions. The cause for the rapid decrease 

t X 

in NO converter efficiency with mileage accumulation is not well 

X 

understood; how much is due to carburetion problems, or to poisoning 

or overtemperature is not precisely known.* 

It appears that the amount of work and effort being performed 

on the dual-catalyst approach by the major manufacturers is somewhat 

diminished over that of two years ago. This may be due either to 

effort being pursued on other, more promising systems, or to a 

decision to wait with the expectation that alternate standards for 

NO will be legislated, 
x 

Other approaches involving the use of a reduction catalyst 

are being worked on by Gould and Questor. Each of these systems is 

designed to carefully control the C0/0^ ratio to the NO catalyst. In 

the Gould system, an 0^ getter is used upstream of the reduction 

catalyst. In the current Gould configuration, the getter consists of 

a small, noble-metal oxidation catalyst. The getter is located in the 

same can as the metallic nickel-based NO converter, with an oxidation 

x 

catalyst located downstream. The getter lowers the 0^ concentration 
entering the NO bed to approximately 0.17, over the range of operating 

X 

conditions experienced in the CVS test (Figure 7.3). This would then 
compensate for the variabilities associated with today's conventional 
carburetors. The latest Gould reduction catalyst (GEM 68) gives over 
907, next NO conversion (Fig. 7.4) when operating at 1250°F over a 

X 

range of C0/0^ of 2 to 6 (corresponding to A/F ratio of 14.2:12.7). 
Results of this system are given in Table 7.4. 

To reduce HC levels to 0.41 g/mi, it would be necessary either 
to use a larger or improved oxidation catalyst or to improve 

*To overcome problems associated with carburetor variability, GM has 
run a dual-catalyst system with feedback control featuring an oxygen 
sensor and variable Venturi carburetor (Table 7.3). 



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TIME 


FIGURE 7.3 Effect of Getter on Inlet CO and 0 ? During Portion 
of CVS Test. Test Conducted on 351 CID Ford Torino, Automatic 
Transmission., 


Source: Reference 54 


PERCENT OXYGEN PERCENT OXYGEN 













75 



FIGURE 7.4 Typical Net N0 X Conversion as a Function of 
Air/Fuel Ratio for a Gem 68. 


Source: 


Reference 54 













76 


TABLE 7.4 


Net NO 

x 


Vehicle 

Mileage 

Conversion 

Efficiency 

CO 

N0 X 

HC* 

73 Datsun 610, IW 2,500 lbs. 

5,600 

85.2 

3.149 

0.354 


No EGR, Manual Transmission 

10,249 

86.0 

1.917 

0.356 


Test at Gould 

15,381 

84.5 

1.906 

0.384 



25,580 

85.5 

3.18 

0.382 


*HC were measured incorrectly and 

are not included. 



Same, Test at EPA after 


HC 

CO 

N0 X 

Economy 

25,580 miles 


0.98 

2.93 

0.41 

21.5 MP 


Average of 3 tests 


REF. 55 









77 


carburetion. Both approaches are now being pursued by Gould. 

Preliminary results with the Gould system on a large car, 1971 
Ford Torino, indicate NO levels of approximately 0.6 g/mi up to 

X 

25,000 miles, with no EGR. Fuel economy of the large car was 
equivalent to that of a 1973 model. Gould's experimentation to date 
has been with stock vehicles, retaining timing while resetting the 
carburetors to give the desired rich carburetion. It would appear 
that if this system were to be applied to a 1975 vehicle with timing 
and other adjustments for optimum economy, some improvements in 
economy would be attained. Conservatively, it would appear that 
levels of 0.4/3.4/1.0 in standard vehicles could be realized with 
economy no worse than 5%-10% below 1975 catalyst vehicles. For 
small cars, 0.41/3.4/0.4 could be attained with the Gould system with 
economy approximately the same as 1975 models of the same weight. 

With the Questor approach, the ratio of C0/0- going to the NO 

Lm X 

converter is controlled with a rich thermal reactor instead of a 
getter. Thus,the Questor system consists of a rich thermal reactor, 
followed by a metallic, nickel-based NO converter, followed by 

X 

another thermal reactor for cleanup of HC and CO. Controlled air 
is injected into the exhaust ports and before the final oxidizing 
thermal reactor. Durability tests of the Questor system are shown 
in Table 7.5. Fuel economy was 8.2 mpg, about 147 0 worse than EPA 
results for average 1974 vehicles in the 5,000-pound weight class. 

Questor is currently testing a newer, more durable reduction 
catalyst which will enable leaner operation (although still on the 
rich side of stoichiometric). Results on a Datsun tested at 2,750- 
pound inertia weight gave, at 8,103 miles: 


HC 

0.16 

CO 

2.97 

NO 

0.28 


78 


TABLE 7.5 


Questor System on 1971, 400 CID 


Mileage 

HC 

CO 

0 

0.085 

3.03 

18,483 

0.400 

2.66 

23,142 

0.235 

1.56 

35,946 

0.158 

3.045 

50,024 

0.294 

2.986 


Pontiac Catalina 

N0 X Comments 

0.365 

0.380 

0.617 NO^ catalyst replaced 

0.419 

0.283 


REF. 56 





79 


Economy here was 18.2 mpg, about equivalent to that of the average 
1974 vehicle in that class. 

It is felt that improved carburetion could help economy of 
both the Gould and Questor systems. Both systems appear capable of 
being certified at levels below 0.41/3.4/1.0. 


8. THREE-WAY CATALYST WITH FEEDBACK 


8.1 Introduction 

Under carefully controlled conditions, a single-bed catalyst is 
able to reduce all three automotive emissions, HC, CO and NO , to 
levels of 0.41, 3.4 and 0.4 g/mi, respectively. Current three-way 
catalysts of this type must be operated with the engine close to 
stoichiometric, as shown in Figure 8.1."^ Control to within +0.1 
A/F ratio is required for successful operation. With the successful 
development of the 0^ sensor and feedback control, which allows the 
required A/F ratio control (Section 5) intensive efforts are underway 
to develop a three-way catalyst with the required durability. This 
three-way catalyst system with feedback has several advantages over 
a dual catalyst system: with only one catalyst, the problem of 
catalyst warm-up and cold-start emissions is alleviated; operation 
at stoichiometric rather than fuel-rich leads to improved fuel 
economy; no air pump is required since enough 0^ is present in the 
exhaust stream; and, feedback control at stoichiometric provides a 
self-maintaining feature, compensating for minor variations in 
engine parameters. 

8.2 Three-Way Catalyst with Electronic Fuel Injection (EFI) 

and Feedback 

Many manufacturers have been able to achieve 1978 levels at 

low mileage, using the 0 sensor feedback and L-jetronic fuel 

^ 38 

injection. Typical results are shown in Table 8.1. 


80 





PERCENT CONVERSION EFFICIENCY 


81 



FIGURE 8.1 Conversion Efficiency of a Three 
Constituent Catalyst. 


Lean 


Source: Reference 57 






82 


TABLE 8.1 



HC 

CO 

NO 

X 

Volkswagen 

0.3 

1.2 

0.2 

Bosch 

0.3 

1.7 

0.3 

Daimler-Benz 

0.4 

1.8 

0.4 

Robert Bosch has 

the most 

advanced 

durabil 


4 cylinder, 1.9 liter 
8 cylinder, 4.8 liter 


that 20,000-mile durability has been demonstrated with a 2,300 lb car 
and 1.9 liter engine with the values shown in Figure 8.2. After that 
period, the NO emissions started to rise for unknown reasons. Bosch 

X 

also made the claim, based on the results of bench tests (Figure 8.3), 

that better catalysts are now available and that durability of 

25,000 miles or more will soon be demonstrated. The data of Figure 

8.2 were obtained with the catalyst dated 10/10/73 in Figure 8.3; 

59 

the catalyst dated 4/2/74 clearly exhibits better performance. 

60 

Ford has been experimenting with an in-house developed 
EFI system anc 
catalyst: 


and 0^ feedback with the 

following 

results 


HC 

CO 

NO 




X 

Feed gas 

2.9 

22 

4.2 

After catalyst 

No EGR 

0.1 

2.0 

0.5 

and for aged 

catalyst 

(100 hrs) 



HC 

CO 

NO 




X 

Feed gas 

3.18 

24 

5.0 

After Catalyst 

No EGR 

0.11 

0.68 

1.34 


Life tests continue. 





83 



10,000 20,000 25,000 


O 

o 




FIGURE 8.2 4-Cylinder Engine, 

1.9 Liter, L-Jetronic, DeGussa OM721, 
Fuel Economy 18.7 mpg, Weight of 
Car 1050 kg. 


Source: Reference 59 















CO (%) NO (ppm) 


84 




TIME (hours) 

FIGURE 8.3 Catalyst Durability. 


Source: Reference 59 






85 


TABLE 8.2 


a. Vega EFI Emission and Economy Results (Low Mileage) 
3000 lb I.W. 


HC CO NO 

x 

Average of 5 emissions tests: 0.23 g/mi 2.58 g/mi 0.32 g/mi 

Fuel Economy: 20.43 mpg @ 0.35 g/mi NO (EGR) 

X 

21.42 mpg @ 0.90 g/mi NO (No EGR) 

X 

Base: 20.50 mpg for '75 Calif. @ 1.4 NO 

X 

20.32 mpg for '75 Federal @ 2.1 NO 

x 

b. Chevrolet 350 C.I.D., V8, 4,500 lb I.W. (Low Mileage) 


HC 

CO 

NO 

MPG 



X 


0.56 

5.1 

0.96 

11.5 

0.47 

4.6 

0.77 

Not available 


REF. 57 


TABLE 8.3 


Comparison of Various Control Schemes (1.9 L Engine) 
All Cars Equipped with L-Jetronic 



Car 1 

Car 2 

Car 3* 

Car 4* 

Stoichio- 

metric 

1975 Model 

Lean 

Lean 


Ratio 

1.05 

1.15-1.2 

1.04 

1.0 

Spark Advance 

4° 

8° 

Double ignition 

8° 

4° delay 

Percent EGR 

3-10 

8 

8 

0 


*Cars 3 and 4 have feedback control 


HC 

0.57 

0.15 

0.2 

0.15 

CO 

6.67 

2.9 

3.02 

1.72 

NO 

1.59 

0.88 

1.16 

0.13 


x 


100% 121% 100% 


Fuel Cons 


89% 








87 


General Motors provided data on a Vega equipped with a three- 
way catalyst, EFI and feedback as shown in Table 8.2. 

Most manufacturers agree that fuel economy of the 0^ sensor - 
L-jetronic feedback control is improved over open-loop controls and 
that 1978 standards can be met with minimum fuel penalty if the three- 
way catalyst aging problem is resolved. 

Bosch provides an interesting comparison of various control 
systems in Table 8.3. The superiority of feedback is evident. 

8.3 Three-Way Catalyst with Mechanical Fuel Injection (MFI) 

and Feedback 

The 0 o sensor output requires the addition of a simple electronic 
control unit and an additional solenoid-operated fuel pump to 
modulate fuel pressure in the control pressure loop of the K-jetronic 
mechanical fuel injection device. The 0 ? sensor feedback system with 
K-jetronic now becomes somewhat more expensive than the equivalent 
L-jetronic feedback control. 

Many manufacturers report that they were able to achieve 1978 
NO standards at low mileage; however, failure occurred because 

X 

of three-way catalyst aging after less than 10,000 miles. Typical 
results are shown in Table 8.4 . 


5 8 

Table 8.4 



HC 

CO 

NO 

X 

MPG 

Saab 

0.1 

1.7 

0.21 

19.3 

Audi 

0.28 

1.0 

0.4 


Volvo 

0.25 

0.8 

0.25 

16.0 


No durability data is available. 

No U.S. manufacturer reported data with the K-jetronic feedback 
system. 






88 


8.4 Three-Way Catalyst with Carburetor and Feedback 

All U.S. manufacturers and some foreign carburetor manufacturers 
are developing carburetors whose settings can be continuously 
adjusted with electrical error signals from an exhaust gas sensor. 

Most electronic carburetors are of the variable Venturi category 
although some work is reported with sonic carburetion. This approach 
is logical since feedback control makes sense only with better 
cylinder-to-cylinder distribution than can be achieved with conventional 
carburetors. W carburetors, sonic carburetors, and hot-spot 
carburetors can provide the needed improved A/F ratio distribution. 

Results from GM with advanced design carburetors, feedback and 
the three-way catalyst are given in Table 8.5~^ (all at low mileage). 

TABLE 8.5 



Car 

Carburetor 

HC 

CO 

NO 

X 

MPG 

4000 

00 

> 

#1 

• 

• 

w 

Mod. Quad 

0.28 

4.85 

0.54 

11.7 

4500 

I.W., V8, 350 CID 

IFC 

0.17 

5.5 

0.69 

11.5 


To summarize: 

In all cases, fuel economy of three-way catalyst systems is good, 
as is driveability. Fuel economy could be improved further by 
the complete elimination of EGR; this may not be possible with 
the large U.S. engines. 

The durability of the 0^ sensor is established; the durability of 
the three-way catalyst is not proven and cannot be predicted. 

The tests of Bosch suggest, however, that a durable catalyst 
may be achievable. 



89 


The cost of feedback control systems may be attractive in 
comparison with more conventional systems because of possible 
elimination of many presently used ancillary controls such as 
fast chokes, altitude compensation, air pumps, EGR, etc. 

The feedback control is a new technology with great potential 
to achieve low emissions with low fuel consumption and 
control-system cost. 


9. ROTARY ENGINES 


9.1 Introduction 

The chief advantages of the rotary engine as an automotive power 
plant lie in its smoother operation, fewer number of parts and 
higher power-to-weight ratio, in comparison to a conventional piston 
engine. However, the engine has a high surface-to-volume ratio, 
contributing to higher HC emissions and lower thermal efficiencies 
in comparison to equivalent piston engines. Bare-engine HC emission 
levels of current rotary engines are approximately four times those 
of equivalent piston engines, whereas CO and NO levels are roughly 

X 

the same as those of piston engines. 

The emissions-control system used on 1974 Mazda rotary engines 
featured a rich exhaust thermal reactor to control HC emissions, with 
the engine operating at an air fuel ratio of approximately 13:1. 
Exhaust emissions measured in 1974 California certification by EPA 
are given in Table 9.1, as well as data from Toyo Kogyo on the same 
model. 

Because of the above-cited problem with high HC emissions and 
high fuel consumption, there does not appear to be a concerted 
movement in the industry towards rotary engines. Though a few 
manufacturers have increased their efforts on rotary engines, most of 
the increased effort has gone into feasibility studies. Ford has 
terminated such a feasibility study during the past year. 

9.2 Near-Term Systems 

Emissions-control systems currently used on rotary engines are 
similar to those used on conventional piston engines; namely, 
catalysts or thermal reactors and EGR. There is some concern about 
the durability of the catalyst-equipped systems since the HC loading 
is so much higher than that of conventional engines. Figure 9.1 
illustrates this problem. With base-engine en ssions of 8-10 g/mi 
HC catalytic converter efficiencies of approximately 90% are required 


90 




91 


TABLE 9.1 


Exhaust Emissions 

of 

the 1974 Mazda 

with Rich 

Thermal 

Reactor 






HC 

CO 

NO 

X 

MPG 

1974 

California 

EPA 

certification 

2.4 

19 

0.9 

10.4 

1974 

Production 

average 

2.5 

14 

1.3 

11.8 


3,000 lb inertia weight 
Engine displacement 80 CID 
Manual transmission 


REFS 


61,62 



92 



BARE ENGINE EMISSIONS (g/mi) 

FIGURE 9.1 HC Conversion Efficiency Requirements. 


Source: Reference 63 




93 


to achieve exhaust HC levels of 0.90 g/mi (California interim 1975 
level). There is clearly little margin for deterioration. 

Thermal reactor systems do not appear to have this problem; 
deterioration factors for these systems are shown in Table 9.2. 
However, the rich reactors currently in use incur a fuel penalty, 
as was shown in Table 9.1. A summary of results from General Motors 
is given in Table 9.3. It can be seen that, at least at low mileage, 
fuel economy of catalyst-equipped rotary engines approaches that of 
equivalent 1975 vehicles equipped with conventional engines. 

Toyo Kogyo is developing a lean-reactor system. This system 
uses an A/F ratio of 16.5:1 to 17:1. Results are shown in Table 9.4. 

9.3 Long-Term Systems 

Some work is being done on more advanced rotary engines systems. 
Most of this effort is being spent on adapting the stratified-charge 
concepts to the rotary engine. Both open-chamber and divided-chamber 
concepts have been tried with reasonable results. Table 9.5 shows 
the outcome of some of this work. 

Figure 9.2 shows the relationship between NO^ level and fuel 
consumption for a typical present rotary-engine powered vehicle and 
similar stratified-charge rotary-engine vehicles. Although a 
significant fuel-consumption improvement is made using the 
stratified-charge principles, the basic relationship between NO 

X 

level and fuel consumption holds. Whenever lower NO^ levels are 
approached, the driveability is seriously impaired even with the 
stratified-charge systems. 

Although the stratified-charge work has shown promising results, 
it is still in the early stages of development. Also, some type of 
external clean-up device (i.e., thermal reactor, catalyst, etc.) is 
still needed to achieve the emissions standards although the bare- 



94 

TABLE 9.2 


Typical Deterioration Factors of 
Thermal Reactor-Equipped Rotary Engines 


Pollutant 


Deterioration Factor 


HC 1.0-1.05 

CO 1.0 - 1.03 

NO 

x 


1.02 - 1.05 






95 


a 

w 


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cu 










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Rotary with Lean Reactor 


96 


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REF. 62 



97 


TABLE 9.5 


Emission and Fuel Consumption Characteristics of an 
Experimental Open-Chamber Stratified-Charge Rotary Engine 


EGR 

m 

0 

7-8% 

20%' 

HC 

(g/mi) 

0.24 

0.22 


CO 

(g/mi) 

1.8 

2.5 


NO 

X 

(g/mi) 

1.5 

0.91 

0.4 

Fuel Consumption (mpg) 

17.5 

16.8 

14.0 


* Bench data only 


REF. 64 




NO y LEVEL (g/mi) 


98 



FUEL CONSUMPTION (mpg) 

FIGURE 9.2 Comparison of N0 X and Fuel Consumption 
Characteristics of Various Rotary Engine Concepts. 


Source: References 62, 63 




99 


engine emissions are undoubtedly lower. It is doubtful if a fully 
developed stratified-charge rotary-engine could be available before 
the early to middle 1980's. 

9.4 Summary 

Most of the rotary-engine effort to date has been concentrated 
on improving durability and fuel consumption. Little effort has 
been spent on understanding the basic combustion process or lowering 
the bare-engine emissions. Most manufacturers appear to be looking 
at the rotary engine for its packaging, performance and potential 
cost advantages rather than as a solution to the emissions problem. 

It appears that rotary-engine systems can meet near-term emissions 
standards with reasonable fuel consumption. Although the advanced 
stratified-charge rotary-engine concepts appear promising, it is 
doubtful whether they can be available until the 1980's. 



10. STRATIFIED-CHARGE ENGINES 


10.1 Introduction and General Background 

a. General — The term "stratified-charge engine" has been 
used for many years in connection with a variety of unconventional 
engine combustion systems. Common to nearly all such systems is 
the combustion of F/A mixtures having a significant gradation or 
stratification in fuel concentration within the engine combustion 
chamber. Hence the term "stratified charge." Historically, the 
objective of stratified-charge-engine designs has been to permit 
spark-ignition-engine operation with average or overall F/A ratios 
lean beyond the ignition limits of conventional combustion systems. 

The advantages of this type of operation will be enumerated shortly. 
Attempts at achieving this objective date back to the first or 
second decade of this century.^ 

More recently, the stratified-charge engine has been 
recognized as a potential means for control of vehicle pollutant 
emissions with minimum loss of fuel economy. As a consequence, the 
various stratified-charge concepts have been the focus of renewed 
interest. 

b. Advantages and disadvantages of lean-mixture operation -- 
Fuel-lean combustion as achieved in a number of the stratified-charge- 
engine designs receiving current attention has both advantages and 
disadvantages when considered from the combined standpoints of 
emissions control, vehicle performance and fuel economy. 

Advantages of lean mixture operation include the following: 

. Excess oxygen contained in lean-mixture combustion gases help 

to promote complete oxidation of hydrocarbons (HC) and carbon 
monoxide (CO) both in the engine cylinder and in the exhaust 
system. 


100 






101 


. Lean-mixture combustion results in reduced peak engine-cycle 

temperatures and can, therefore, yield lowered nitrogen oxide 

(NO ) emissions, 
x 

. Thermodynamic properties of lean-mixture-combustion products 

are favorable from the standpoint of engine-cycle thermal 
efficiency (reduced extent of dissociation and higher effective 
specific heats ratio). 

. Lean-mixture operation can reduce or eliminate the need for air 

throttling as a means of engine load control. The consequent 
reduction in pumping losses can result in significantly 
improved part-load fuel economy. 

Disadvantages of lean mixture operation include the 

following: 

. Relatively low-combustion gas temperatures during the engine 

cycle expansion and exhaust processes can result from extreme¬ 
ly lean operation. As a consequence, HC oxidation reactions are 
retarded and unburned HC exhaust emissions can be excessive. 

. Engine modifications aimed at raising exhaust temperatures for 

improved HC emissions control (retarded ignition timing, lowered 
compression ratio, protracted combustion) necessarily impair 
engine fuel economy. 

. If lean-mixture operation is to be maintained over the entire 

engine load range, maximum power output and, hence, vehicle 
performance are significantly impaired. 

Lean-mixture exhaust gases are not amenable to treatment by 
existing reducing catalysts for NO emissions control. 

X 



102 


. Lean-mixture combustion, if not carefully controlled, can 

result in formation of undesirable odorant materials that appear 
in significant concentrations in the engine exhaust. Diesel 
exhaust odor is typical of this problem and is thought to derive 
from lean-mixture regions of the combustion chamber. 

. Measures required for control of NO^ emissions to low levels 

(for example, EGR) can accentuate the above HC and odorant 
emissions problems. 

Successful development of the several stratified-charge- 

engine designs now receiving serious attention will depend very much 

on the balance that can be achieved among the foregoing favorable 

and unfavorable features of lean combustion. This balance will, of 

course, depend ultimately on the standards or goals that are set for 

emissions control, fuel economy, vehicle performance and cost. Of 

particular importance are the relationships between three factors-- 

unburned hydrocarbon (UBHC) emissions, NO emissions, and fuel 

x 

economy. 

c. Stratified-charge-engine concepts -- Charge stratification 
permitting lean-mixture operation has been achieved in a number of 
ways using differing concepts and design configurations. 

Irrespective of the means used for achieving charge 
stratification, two distinct types of combustion processes can be 
identified. One approach involves ignition of a small and localized 
quantity of flammable mixture which, in turn, serves to ignite a 
much larger quantity of adjoining or surrounding fuel-lean-mixture-- 
too lean for ignition under normal circumstances. Requisite mixture 
stratification has been achieved in several different ways ranging 
from use of fuel injection directly into "open" combustion chambers 
to use of dual combustion chambers divided physically into rich and 
lean-mixture regions. Under most operating conditions, the overall 



103 


or average F/A ratio is fuel-lean and the advantages enumerated above 
for lean operation can be realized. 

A second approach involves timed staging of the combustion 

process. An initial rich-mixture stage in which major combustion 

reactions are completed is followed by rapid mixing of rich-mixture 

combustion products with an excess of air. Mixing and the resultant 

temperature reduction can, in principle, occur so rapidly that 

minimum opportunity for NO formation exists and, as a consequence, 

NO emissions are low. Sufficient excess air is made available to 
x 

encourage complete oxidation of HC and CO in the engine cylinder and 
exhaust system. The staged combustion concept has been specifically 
exploited in divided-chamber or large-volume prechamber engine 
designs. But it will be seen that staging is also inherent to some 
degree in other types of stratified-charge engines. 

The foregoing would indicate that stratified-charge engines 
can be categorized either as "lean-burn" engines or "staged-combustion" 
engines. In reality, the division between concepts is not so clear 
cut. Many engines encompass features of both concepts. 

d. Scope -- During the past several years, a large number of 
engine designs falling into the broad category of stratified-charge 
engines have been proposed. Many of these have been evaluated by 
competent organizations and have been found lacing in one or more 
important areas. A much smaller number of stratified-charge engine 
designs have shown promise for improved emissions control and fuel 
economy with acceptable performance, durability and production 
feasibility. These are currently receiving intensive research 
and/or development efforts by major organizations--both domestic 
and foreign. 

The purpose of this Consultant Report is not to enumerate 
and describe the many variations of stratified-charge engine design 
that have been proposed in recent years. Rather, it is intended to 



104 


focus on those engines that are receiving serious development efforts 
and for which a reasonably large and sound body of experimental data 
has evolved. It is hoped that this approach will lead to a reliable 
appraisal of the potential for stratified-charge engine systems. 

10.2 Open-Chamber, Stratified-Charge Engines 

a. General -- From the standpoint of mechanical design, 

stratified-charge engines can be conveniently divided into two types: 

open-chamber and dual-chamber. The open-chamber, stratified-charge 

engine has a long history of research interest. Those engines 

reaching the most advanced stages of development are probably the 

66,67 

Ford-programmed combustion process (PROCO) and Texaco s 

68 69 

controlled combustion process (TCCS). ’ Both engines employ a 
combination of inlet air swirl and direct timed combustion-chamber 
fuel injection to achieve a local fuel-rich ignitable mixture near 
the point of ignition. For both engines, the overall mixture ratio 
under most operating conditions is fuel lean. 

Aside from these general design features that are common to 
the two engines, details of their respective engine-cycle processes 
are quite different, and these differences affect engine performance 
and emissions characteristics. 

b. The Ford PROCO engine 

(1) Descriptions -- The Ford PROCO engine is an outgrowth 
of a stratified-charge development program initiated by Ford in the 
late 1950's. The development objective at that time was an engine 
having diesel-like fuel economy but with performance, noise levels, 
and driveability comparable to that of conventional engines. In the 
1960's, objectives were broadened to include exhaust-emissions 
control. 





105 


A recent developmental version of the PROCO engine 
is shown in Figure 10-1. Fuel is injected directly into the 
combustion chamber during the compression stroke resulting in 
vaporization and formation of a rich mixture cloud or kernel in the 
immediate vicinity of the spark plug(s). A flame initiated in this 
rich-mixture region propagates outwardly to the increasingly fuel- 
lean regions of the chamber. At the same time, high air-swirl 
velocities resulting from special orientation of the air inlet system 
help to promote rapid mixing of fuel-rich combustion products with 
excess air contained in the lean region. Air swirl is augmented by 
the "squish" action of the piston as it approaches the combustion- 
chamber roof at the end of the compression stroke. The effect of 
rapid mixing can be viewed as promoting a second stage of combustion 
in which rich mixture-zone products mix with air contained in lean 
regions. Charge stratification permits operation with very lean F/A 
mixtures with attendant fuel economy and emissions advantages. In 
addition, charge stratification and direct fuel injection permit use 
of high compression ratios with gasolines of moderate octane quality 
again giving a substantial fuel economy advantage. 

Present engine operation includes enrichment under 
maximum power-demand conditions to mixture ratios richer than 
stoichiometric. Performance, therefore, closely matches that of 
conventionally powered vehicles. 

Nearly all PROCO development plans at the present time 
include use of oxidizing catalysts for HC emissions control. For a 
given HC emissions standard, oxidizing catalysts permit use of leaner 
A/F ratios (lower exhaust temperatures) together with fuel injection 
and ignition timing characteristics optimized for improved fuel 
economy. 

(2) Emissions and fuel economy -- Figure 10-2 is a plot 
of PROCO vehicle fuel economy versus NO emissions based on the 

X 


106 


Fuel Injector 



Source: Reference 71 








































107 



References 70, 71 






















108 


Federal CVS-CH test procedure. Also included are corresponding HC 

and CO emissions levels. Only the most recent test data have been 

plotted since these are most representative of current program 

directions and also reflect most accurately current emphasis on 

improved vehicle fuel economy.^ For purposes of comparison, 

average fuel economies for 1974 production vehicles weighing 4,500 

72 

pounds and 5,000 pounds have been plotted. (The CVS-C values 
reported in Reference 72 have been adjusted by 57 0 to obtain estimated 
CVS-CH values.) 

Data points to the left on Figure 10-2 at the 0.4 g/mi 

NO level represent efforts to achieve statutory 1977 emissions 
X 70 

levels. While the NO target of 0.4 g/mi was met, the requisite 

x 

use of EGR resulted in HC emissions above the statutory level. 

A redefined NO target of 2.0 g/mi has resulted in 

x 

the recent data points appearing in the upper right-hand region of 
Figure 10-2. The HC and CO emissions values listed are without 
exhaust oxidation catalysts. Assuming catalyst conversion 
efficiencies of 507 o -607 o at the end of 50,000 miles of operation, HC 
and CO levels will approach but not meet statutory levels. At the 
indicated levels of emissions-control fuel economy is improved some 
407 o to 45% relative to 1974 production-vehicle averages for the same 
weight class. 

The cross-hatched, horizontal band appearing across 
the upper part of Figure 10-2 represents the reductions in NO 
emissions achievable with use of EGR is HC emissions are unrestricted. 
The statutory 0.4 g/mi level can apparently be achieved with this 
engine with little or no loss of fuel economy but with significant 
increases in HC emissions. The HC increase is ascribed to the 
quenching effect of EGR in lean-mixture regions of the combustion 
chamber. 


109 


(3) Fuel requirements -- Current PROCO engines operated 
with 11:1 compression ratio yield a significant fuel economy 
advantage over conventional production engines at current compression 
ratios. According to Ford engineers, the PROCO engine at this 
compression ratio is satisfied by typical full-boiling commercial 
gasolines of 91 RON rating. Conventional engines are limited to 
compression ratios of about 8:1 and possibly less for operation on 
similar fuels. 

Results of preliminary experiments indicate that the 
PROCO engine may be less sensitive to fuel volatility than conventional 
engines--an important factor in flexibility from the standpoint of 
the fuel supplier. 

(4) Present status — Present development objectives are 

two-fold: 

. Develop calibrations for alternate emissions target levels 
to determine the fuel economy potential associated with 
each level of emissions control. 

. Convert engine and auxiliary systems to designs feasible 
for high-volume production. 

c. The Texaco TCCS stratified-charge engine 

(1) General description -- Like the Ford PROCO engine, 
Texaco's TCCS system involves coordinated air swirl and direct 
combustion-chamber, fuel injection to achieve charge stratification. 
Inlet-port-induced cylinder air swirl rates typically approach ten 
times the rotational engine speed. A sectional view of the TCCS 
combustion chamber is shown in Figure 10-3. 

Unlike the PROCO engine, fuel injection in the TCCS 
engine begins very late in the compression stroke -- just before the 
desired time of ignition. As shown in Figure 10-4, the first portion 



110 



FIGURE 10.3 Texaco TCCS Engine. 















































Ill 



FIGURE 10.4 Texaco Controlled Combustion System. 


Source 


Reference 73 




















112 


of fuel injected is immediately swept by the swirling air into the 
spark plug region where ignition occurs and a flame front is 
established. The continuing stream of injected fuel mixes with 
swirling air and is swept into the flame region. In many respects, 
the Texaco process resembles the spray burning typical of diesel 
combustion with the difference that ignition is achieved by energy 
from an electric spark rather than by high compression temperatures. 
The Texaco engine, like the diesel engine, does not have a significant 
fuel octane requirement. Further, use of positive spark ignition 
obviates fuel cetane requirements characteristic of diesel engines. 

The resultant flexibility of the TCCS engine regarding fuel 
requirements is a significant attribute. 

In contrast to the TCCS system, Ford's PROCO system 
employs relatively early injection, vaporization, and mixing of fuel 
with air. The combustion process more closely resembles the 
premixed flame propagation typical of conventional gasoline engines. 
The PROCO engine, therefore, has a definite fuel octane requirements 
and cannot be considered a multifuel system. 

The TCCS engine operates with high compression ratios 
and with little or no inlet air throttling except at idle conditions. 
As a consequence, fuel economy is excellent--both at full load and 
under part-load operating conditions. 

(2) Exhaust emissions and fuel economy -- Low exhaust 
temperatures characteristic of the TCCS system have necessitated use 
of exhaust oxidation catalysts for control of HC emissions to low 
levels. All recent development programs have, therefore, included 
use of exhaust oxidation catalysts, and most of the data reported 
here represent tests with catalysts installed or with engines tuned 
for use with catalysts. 

Figures 10-5 and 10-6 present fuel economy data at 
several exhaust emissions levels for two vehicles--a U.S. Army M-151 


Mnximum Economy Sotting 


113 



(6dw) HD-SAD 'AW0N003 13Hd 


FIGURE 10.5 Texaco TCCS Powered Cricket Vcliicle. 






141 CID, 10:1 CR 
2750 lb Inertia Weight 


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vehicle with naturally aspirated 4-cylinder TCCS conversion, and a 

73 74 

Plymouth Cricket with turbocharged 4-cylinder TCCS engine. * 

Turbocharging has been used to advantage to increase maximum power 

output. Also plotted in these figures are average fuel economies 

72 

for 1974 production vehicles of similar weight. 

When optimized for maximum fuel economy, the TCCS 

vehicles can meet NO levels of about 2.0 g/mi. It should be noted 

x 

that these are relatively lightweight vehicles and that increasing 
vehicle weight to the 4,000-5,000-pound level could result in 
significantly increased NO emissions. Figures 10-5 and 10-6 both 

X 

show that engine modifications for reduced NO^ levels including 
retarded combustion timing, EGR and increased exhaust back pressure 
result in substantial fuel economy penalties. 

For the naturally aspirated engine, reducing NO 

X 

emissions from the 2.0 g/mi level to 0.4 g/mi incurred a fuel 
economy penalty of 20%. Reducing NO from the turbocharged engine 

X 

from 1.5 g/mi to 0.4 g/mi gave a 25% fuel economy penalty. Fuel 
economies for both engines appear to decrease uniformly as NO 

x 

emissions are lowered. 

For the current TCCS systems, most of the fuel 

economy penalty associated with emissions control can be ascribed 

to control of NO emissions, although several of the measures used 

x 

for NO control (retarded combustion timing and increased exhaust 

X 

back pressure) also help to reduce HC emissions. HC and CO emissions 
are effectively controlled with oxidation catalysts resulting in 
relatively minor reductions in engine efficiency. 


(3) TCCS fuel requirements -- The TCCS engine is unique 
among stratified-charge systems in its multifuel capability. 
Successful operation with a number of fuels ranging from gasoline 
to No. 2 diesel has been demonstrated. Table 10-1 lists emissions 
levels and fuel economies obtained with a turbocharged TCCS-powered 


116 


M-151 vehicle when operated on each of four different fuels. 
These fuel encompass wide ranges in gravity, volatility, octane 
number and cetane level as shown in Table 10-2. 


TABLE 10-1 


Emissions and Fuel Economy of Turbocharged 
TCCS Engine-Powered Vehicle 

Emissions 


Fuel 

HC 

£/mi 2 

CO 

NO 

X 

Fuel Economy 
2 

mpg 

Gasoline 

0.33 

1.04 

0.61 

19.7 

JP-4 

0.26 

1.09 

0.50 

20.2 

100-600 

0.14 

0.72 

0.59 

21.3 

No. 2 Diesel 

0.27 

1.14 

0.60 

23.0 


^M-151 vehicle, 8 degrees combustion retard, 16% light 
load EGR, two catalysts. 

? 

CVS-CH, 2,750 pounds inertia weight. 


REF. 74 






117 


TABLE 10-2 


Fuel Specifications for 
TCCS Emission Tests 


Gasoline 

100-600 

JP-4 

No. 2 

Diesel 

Gravity, °API 

58.8 

48.6 

54.1 

36.9 

Sulfur, % 

- 

0.12 

0.020 

0.065 

Distillation, °F 





IBP 

86 

110 

136 

390 

10% 

124 

170 

230 

435 

50% 

233 

358 

314 

508 

90% 

342 

544 

459 

562 

EP 

388 

615 

505 

594 

TEL, g/gal. 

0.002 

0.002 

- 

- 

Research Octane 

91.2 

57 

- 

- 

Cetane No. 

- 

35.6 

- 

48.9 REF. 74 


Generally, the emissions levels were little affected by the wide 
variations in fuel properties. Vehicle fuel economy varied in 
proportion to fuel energy content. 

As stated above, the TCCS engine is unique in its 
multifuel capability. The results of Tables 10-1 and 10-2 demonstrate 
that the engine has neither significant fuel octane nor cetane 
requirements and, further, that it can tolerate wide variations in 
fuel volatility. The flexibility offered by this type of system 
could be of major importance in future years. 









118 


(4) Durability, performance, production readiness — 
Emissions-control-system durability has been demonstrated by mileage 
accumulation tests. Ignition-system service is more severe than for 
conventional engines due to heterogeneity of the F/A mixture and also 
to the high compression ratios involved. The ignition system has 
been the subject of intensive development and significant progress in 
system reliability has been made. 

A preproduction, prototype engine employing the TCCS 
process is now being developed by the Hercules Division of White 
Motors Corporation, under contract to the U.S. Army Tank Automotive 
Command. Southwest Research Institute will conduct reliability 
tests on the White-developed engines when installed in military 
vehicles. 

10.3 Small Volume Prechamber Engines (3-Valve Prechamber Engines, 

Jet Ignition Engines, Torch Ignition Engines) 

a. General -- A number of designs achieve charge stratification 
through division of the combustion region into two adjacent chambers. 
The emissions reduction potential for two types of dual-chamber 
engines has been demonstrated. First, in a design traditionally 
called the "prechamber engine," a small auxiliary or ignition chamber 
equipped with a spark plug communicates with the much larger main 
combustion chamber located in the space above the piston (Figure 10-7). 
The prechamber, which typically contains 5%-15% of the total 
combustion volume, is supplied with a small quantity of fuel-rich 
ignitable F/A mixture while a large quantity of very lean and 
normally unignitable mixture is applied to the main chamber above 
the piston. Expansion of high-temperature flame products from the 
prechamber leads to ignition and burning of the lean main chamber 
F/A charge. Ignition and combustion in the lean, main-chamber region 
are promoted both by the high temperatures of prechamber gases and by 





119 



FIGURE 10.7 


3-Valve Prechamber Engine Concept. 





























120 


the mixing that accompanies the jet-like motion of prechamber products 
into the main chamber. 

Operation with lean overall mixtures tend to limit peak 
combustion temperatures, thus minimizing the formation of nitric 
oxide. Further, lean-mixture combustion products contain sufficient 
oxygen for complete oxidation of HC and CO in the engine cylinder 
and exhaust system. 

It should be reemphasized here that a traditional problem 
with lean mixture engines has been low exhaust temperatures which 
tend to quench HC oxidation reactions leading to excessive emissions. 

Control of HC emissions to low levels requires a retarded 
or slowly developing combustion process. The consequent extension 
of heat release into late portions of the engine cycle tends to raise 
exhaust gas temperatures, thus promoting complete oxidation of HC 
and CO. 

b. Historical background and current status 


(1) Early development objectives and engine designs -- The 

prechamber, stratified-charge engine has existed in various forms 

6 5 

for many years. Early work by Ricardo indicated that the engine 

could perform very efficiently within a limited range of carefully 

controlled operating conditions. Both fuel-injected and carbureted 

prechamber engines have been built. A fuel-injected design 

initially conceived by Brodersen^ was the subject of extensive 

76 77 

study at the University of Rochester for nearly a decade. * 
Unfortunately, the University of Rochester work was undertaken 
prior to widespread recognition of the automobile emissions problem, 
and, as a consequence, emissions characteristics of the Brodersen 
engine were not determined. Another prechamber engine receiving 

7 8 

attention in the early 1960's is that conceived by R. M. Heintz. 

The objectives of this design were reduced HC emissions, increased 



121 


fuel economy and more flexible fuel requirements. 

Experiments with a prechamber engine design called 

79 

"the torch-ignition engine" were reported in the U.S.S.R. by Nilov 

80 

and later by Kerimov and Mekhtier. This designation refers to the 

torch-like jet of hot combustion gases issuing from the precombustion 

81 

chamber upon ignition. In a recent publication, Varshaoski £t al . 
have presented emissions data obtained with a torch-ignition engine. 
These data show significant pollutant reductions relative to 
conventional engines; however, their interpretation in terms of 
requirements based on the U.S. emissions test procedure is not clear. 

(2) Current developments -- A carbureted three-valve, 

prechamber engine, the Honda CVCC system, has received considerable 

82 

recent attention as a potential low-emissions power plant. This 
system is illustrated in Figure 10-8. Honda's current design 
employs a conventional engine block and piston assembly. Only the 
cylinder head and fuel inlet system differ from current automotive 
practice. Each cylinder is equipped with a small precombustion 
chamber communicating by means of an orifice with the main combustion 
chamber situated above the piston. A small inlet valve is located 
in each prechamber. Larger inlet and exhaust valves typical of 
conventional automotive practice are located in the main combustion 
chamber. Proper proportioning of F/A mixture between prechamber 
and main chamber is achieved by a combination of throttle control 
and appropriate inlet valve timing. A relatively slow and uniform 
burning process giving rise to elevated combustion temperatures late 
in the expansion stroke and during the exhaust process is achieved. 
High temperatures in this part of the engine cycle are necessary 
to promote complete oxidation of HC and CO. It should be noted that 
these elevated exhaust temperatures are necessarily obtained at the 
expense of a fuel economy penalty. 


122 



FIGURE 10.8 Honda CVCC Engine. 


Source: Reference 86 




















































123 


To reduce HC and CO emissions to required levels, it 
has been necessary for Honda to employ specially designed inlet and 
exhaust systems. Supply of extremely rich F/A mixtures to the 
precombustion chambers requires extensive inlet manifold heating to 
provide adequate fuel vaporization. This is accomplished with a heat 
exchange system between inlet and exhaust streams. 

To promote maximum oxidation of HC and CO in the lean 
mixture CVCC engine exhaust gases, it has been necessary to conserve 
as much exhaust heat as possible and also to increase exhaust 
manifold residence time. This has been done by using a relatively 
large exhaust manifold fitted with an internal heat shield or liner 
to minimize heat losses. In addition, the exhaust ports are 
equipped with thin metallic liners to minimize loss of heat from 
exhaust gases to the cylinder heat casting. 

Engines similar in concept to the Honda CVCC system 
are under development by other companies including Toyota and Nissan 
in Japan and General Motors and Ford in the United States. 

Honda presently markets a CVCC-powered vehicle in 
Japan and plans U.S. introduction in 1975. Other manufacturers, 
including General Motors and Ford in the U.S., hafe stated that 
CVCC-type engines could be manufactured for use in limited numbers 
of vehicles by as early as 1977 or 1978. 

c. Emissions and fuel economy with CVCC-type engines 

(1) Recent emissions test results — Results of emissions 

tests with the Honda engine have been very promising. The emissions 

levels shown in Table 10-3 are typical and demonstrate that the 

Honda engine can meet statutory HC and CO standards and can approach 

83 

the statutory NO standard. Of particular importance, durability 

X 

of this system appears excellent as evidenced by the high mileage 
emissions levels reported in Table 10-3, Any deterioration of 



124 


emissions after 50,000 miles of engine operation was slight 
and apparently insignificant. 



TABLE 10- 

-3 



Honda Compound Vortex-Controlled 
Combustion-Powered Vehicle^ Emissions 




Emissions,^ 

Fuel Economy, 
mPB 



g/mi 

1975 

1972 


HC 

CO NO 

X 

FTP 

FTP 

3 

Low Mileage Car No. 3652 

0.18 

2.12 0.89 

22.1 

21.0 

50,000-Mile Car 4 No. 2034 

0.24 

1.75 0.65 

21.3 

19.8 

1976 Standards 

0.41 

3.4 2.0 

- 

- 

1977 Standards 

0.41 

3.4 0.4 



‘''Honda Civic vehicles. 

^1975 CVS-XH procedure with 

3 

Average of five tests. 

4 

Average of four tests. 

2000-lb 

inertia weight. 

REF. 

83 

Recently, the 

EPA has 

tested a larger 

vehicle 



converted to the Honda system. This vehicle, a 1973 Chevrolet 

Impala with a 300-CID V-8 engine, was equipped with cylinder heads 

and an induction system built by Honda. The vehicle met the 1976 

interim federal emissions standards though NO levels were 

x 

substantially higher than for the much lighter-weight Honda Civic 
vehicles. 








125 


Results of development tests conducted by General 

85 

Motors are shown in Table 10-4. These tests involved a 5,000 lb 
Chevrolet Impala with stratified-charge engine conversion. HC and CO 
emissions were below 1977 statutory limits, while NO^ emissions 
ranged from 1.5 to 2.0 g/mi. Average CVS-CH fuel economy was 11.2 
miles per gallon. 


TABLE 10-4 

Emissions and Fuel Economy for 

Chevrolet Impala Stratified- 

Charge Engine Conversion 







Exhaust 

Emissions 

g/mi 1 


Fuel 

Economy, 

Test 

HC 

CO 

NO 

X 

mpg 

1 

0.20 

2.5 

1.7 

10.8 

2 

0.26 

2.9 

1.5 

11.7 

3 

0.20 

3.1 

1.9 

11.4 

4 

0.29 

3.2 

1.6 

10.9 

5 

0.18 

2.8 

1.9 

11.1 

Average 

0.23 

2.9 

1.7 

11.2 

1 CVS-CH, 5,000 

-lb inertia weight 


REF. 85 


(2) HC control has a significant impact on fuel economy - 

In Figure 10-9, fuel economy data for several levels of HC emissions 

86 87 

from CVCC-type stratified-charge engines are plotted. ’ At the 
1.0 g/mi HC level, stratified-charge engine fuel economy appears 













NO -1.4 


126 





127 


better than the average fuel economy for 1973-74 production vehicles 

of equivalent weight. Reduction of HC emissions below the 1.0 g/mi 

level necessitates lowered compression ratios and/or retarded ignition 

timing with a consequent loss of efficiency. For the lightweight 

(2,000-lb) vehicles, the 0.4 g/mi HC emissions standard can be met with 

a fuel economy of 25 mpg, a level approximately equal to the average 

72 

of 1973 production vehicles in this weight class. For heavier cars, 
the HC emissions versus fuel economy trade-off appears less favorable. 

A fuel economy penalty of 107, relative to 1974 production vehicles in 
the 2,750-lb weight class is required to meet the statutory 0.4 g/mi 
HC level. 

(3) Effect of NO emissions control on fuel economy -- Data 

^ 86 
showing the effect of NO emissions control appear in Figure 10-10. 

X 

These data are based on modifications of a Honda CVCC-powered Civic 
vehicle (2,000-lb test weight) to meet increasingly stringent NO 

X 

standards ranging from 1.2 g/mi to as low as 0.3 g/mi. For all tests, 
HC and CO emissions are within the statutory 1977 standards. 

NO control as shown in Figure 10-10 has been effected 

x 

by use of EGR in combination with retarded ignition timing. It is 

clear that control of NO emissions to levels below 1.0 to 1.5 g/mi 

x 

results in significant fuel economy penalties. The penalty increases 
uniformly as NO^ emissions are reduced and appears to be 257. or more 
as the 0.4 g/mi NO level is approached. 

X 

It should be emphasized that the data of Figure 10-10 
apply specifically to a 2,000-lb vehicle. With increased vehicle 
weight, NO emissions control becomes more difficult and the fuel 

X 

economy penalty more severe. The effect of vehicle weight on NO^ 
emissions is apparent when comparing the data of Table 10-3 for 2,000- 
lb vehicles with that of Table 10-4 for a 5,000-lb vehicle. While HC 
and CO emissions for the two vehicles are roughtly comparable, there 
is over a factor of two difference in average NO emissions. 

X 


128 



FIGURE 10.10 Fuel Economy Versus N0 X Emissions for Honda CVCC Powered 
Vehicles. 


Source: Reference 86 




129 


d. Fuel requirements -- To meet present and future U.S. 
emissions-control standards, compression ratio and maximum ignition 
advance are limited by HC emissions control rather than by the octane 
quality of existing gasolines. CVCC engines tuned to meet 1975 
California emissions standards appear to be easily satisfied with 
presently available 91 RON commercial unleaded gasolines. 

CVCC engines are lead-tolerant and have completed emissions 
certification test programs using leaded gasolines. However, with 
the low octane requirement of the CVCC engine as noted above, the 
economic benefits of lead antiknock compounds are not realized. 

It is possible that fuel volatility characteristics may be 
of importance in relation to vaporization within the high-temperature, 
fuel-rich regions of the prechamber cup, inlet port and prechamber 
inlet manifold. However, experimental data on this question do not 
appear to be available at present. 

10.4 Divided-Chamber Staged Combustion Engines (Large-Volume 

Prechamber Engines, Fuel-Injected Blind Prechamber Engines ) 

a. General -- Dual-chamber engines of a type often called 
"divided-chamber" or "large-volume prechamber" employ a two-stage 
combustion process. Here initial rich-mixture combustion and heat 
release (first stage of combustion) are followed by rapid dilution of 
combustion products with relatively low-temperature air (second 
state of combustion). The object of this engine design is to effect 
the transition from overall rich combustion products to overall 
lean products with sufficient speed that time is not available for 
formation of significant quantities of NO. During the second low- 
temperature, lean stage of combustion, oxidation of HC and CO goes 
to completion. 

An experimental divided-chamber engine design that has been 






130 


87,88 

built and tested is represented schematically in Figure 10-11. 

A dividing orifice (3) separates the primary combustion chamber (1) 
from the secondary combustion chamber (2), which includes the 
cylinder volume above the piston top. A fuel injection (4) supplies 
fuel to the primary chamber only. 

Injection timing is arranged such that fuel continuously 
mixes with air entering the primary chamber during the compression 
stroke. At the end of compression, as the piston nears its top 
center position, the primary chamber contains an ignitable F/A 
mixture while the secondary chamber adjacent to the piston top 
contains only air. Following ignition of the primary chamber mixture 
by a spark plug (6) located near the dividing orifice, high- 
temperature, rich-mixture combustion products expand rapidly into 
and mix with the relatively cool air contained in the secondary 
chamber. The resulting dilution of combustion products with attendant 
temperature reduction rapidly suppresses formation of NO. At the 
same time, the presence of excess air in the secondary chamber tends 
to promote complete oxidation of HC and CO. 

b. Exhaust emissions and fuel economy -- Results of limited 

research conducted both by university and industrial laboratories 

indicate that NO reductions of as much as 80%-957 o relative to 

x 

conventional engines are possible with the divided-chamber staged 

combustion process. Typical experimentally determined NO emissions 

89 x 

levels are presented in Figure 10-12. Here NO emissions for two 

x 

different divided-chamber configurations are compared with typical 
emissions levels for conventional uncontrolled automobile engines. 

The volume ratio, g appearing as a parameter in Figure 10-12, 
represents the fraction of total combustion volume contained in 
the primary chamber. For g values approaching 0.5 or lower, NO 

X 

emissions reach extremely low levels. However, maximum power output 
capability for a given engine size decreases with decreasing g values. 



131 


Fuel Injector 



Source 


References 87, 88 
















































132 



FIGURE 10.12 Comparison of Conventional and 

Divided Combustion Chamber NO Emissions. 

x 

Source: Reference 90 






133 


Optimum primary chamber volume must ultimately represent a compromise 
between low emissions levels and desired maximum power output. 

HC, and particularly CO, emissions from the divided-chamber 
engine are substantially lower than conventional engine levels. 
However, further detailed work with combustion-chamber geometries 
and fuel-injection systems will be necessary to fully evaluate 
the potential for reduction of these emissions. 

Recent tests by Ford Motor Company show that the large 
volume prechamber engine may be capable of better HC emissions 
control and fuel economy than their PROCO engine. This is shown 

OO 

by the laboratory engine test comparison of Table 10- 57 


TABLE 10-5 


Single-Cylinder Low Emissions 
Engine Tests 




N0 X 

Emissions, 


Fuel 



Reduction 

g/1. hp-hr 


Economy, 

Engine 


Me thod 

NO 

X 

HC 

CO 

lb/1, hp-hr 

PROCO 


EGR 

1.0 

3.0 

13.0 

0.377 

Divided 

Chamber 

None 

1.0 

0.4 

2.5 

0.378 

PROCO 


EGR 

0.5 

4.0 

14.0 

0.383 

Divided 

Chamber 

None 

0.5 

0.75 

3.3 

0.377 REF. 83 


Fuel-injection-spray characteristics are critical to the 

control of HC emissions from this type of engine, and Ford's success 

in this regard is probably due in part to use of the already highly 

developed PROCO gasoline injection system. Figure 10-13 is a cutaway 

view of Ford's adaptation of a 400-CID V-8 engine to the divided- 

90 

chamber system. 



















400 CID LARGE VOLUME PRE-CHAMBER 


134 



FIGURi 10.13 






135 


Volkswagen (VW) has recently published results of a 


91 


program aimed at development of a large-volume prechamber engine. 

In the VW adaptation, the primary chamber which comprises about 307, 
of the total clearance volume is fueled by a direct, time injection 
system, and auxiliary fuel for high-power output conditions is 
supplied to the cylinder region by a carburetor. 


Table 10- 6 presents emissions data for both air-cooled 

92 

and water-cooled versions of VW's divided-chamber engine. Emissions 


levels, while quite low, do not meet the ultimate 1978 statutory U.S. 
standards. 


TABLE 10-6 


Volkswagen Large-Volume 


Prechamber Engine Emissions 


Exhaust 



Engine HC CO N0 y 


Engine Specifications 


1.6 Liter 
Air-Cooled 


2.0 5.0 0.9 


chamber 


8.4:1 compression ratio, pre 


287 0 of total 


clearance volume, conventional 
exhaust manifold, direct pre¬ 
chamber fuel injection 


2.0-Liter 

Water-Cooled 


1.0 4.0 1.0 


9:1 compression ratio, prechamber 
volume 287. of total clearance 
volume, simple exhaust manifold 
reactor, direct prechamber fuel 
injection 


1 


CVS -CH 


REF. 92 














136 


c • Problem Areas 

A number of major problems inherent in the large volume 
prechamber engine remain to be solved. These problems include the 
following: 

. Fuel injection spray characteristics are critically important 
to achieving acceptable HC emissions. The feasibility of 
producing a satisfactory injection system has not been 
established. 

. Combustion noise due to high turbulence levels and, hence, 
high rates of heat release and pressure rise in the 
prechamber, can be excessive. It has been shown that the 
noise level can be modified through careful chamber design 
and combustion event timing. 

. If the engine is operated with prechamber fuel injection as 
the sole fuel source, maximum engine power output is 
limited. This might be overcome by auxiliary carburetion 
of the air inlet for maximum power demand or possibly by 
turbocharging. Either approach adds to system complexity. 

. The engine is characterized by low exhaust temperatures 
typical of most lean mixture engines. 


/ 



11. DIESEL ENGINES 


11.1 Introduction 

Many techniques have been sought for reducing the harmful 
emissions from passenger cars in an effort to clean the air. Exhaust- 
emissions standards have been set by the federal government and the 
state of California for three species: hydrocarbon (HC), carbon 
monoxide (CO) and nitrogen oxides (NO ). It is expected that other 

X 

species which are equally or even more harmful than these will be 
controlled in the future. 

The regulated and nonregulated emissions from diesel-powered 
cars are studied in this Section. The fuel economy and initial and 
maintenance costs of the diesel are compared with the gasoline engine. 
Finally, the intrinsic problem areas associated with the auto-ignition 
process in the diesel engine are examined. 

The approach taken in this Section is to compare the characteristics 
of the diesel-powered cars with those of cars powered by regular 
gasoline engines, stratified-charge engines, Wankel, or gas turbine 
engines. 

11.2 Regulated Emissions 

93 

a. General -- Table 11.1 and Figure 11.1 give a summary of tests 

carried out by EPA-Ann Arbor, and recent results obtained from the 

manufacturers. The Mercedes 220D and 240D and Datsun-Nissan 220C 

have an inertia weight of 3,500 lb, and the Peugeot 504D and Opel 

Rekord 2100D have an inertia weight (I.W.)of 3,000 lb. All of these 

engines have four cylinders. The hydrocarbon emission from the 

Peugeot 504D was 3.1 g/mi which is very high compared to all other 

94 

diesel-powered cars. Recent results by Southwest Research showed 
that the Peugeot 504D produced 2.0 g/mi HC. Peugeot Inc. reported 
at a meeting of foreign manufacturers held by the Committee on Motor 
Vehicles Emissions May 21-23, 1974, that with modifications, their 


137 





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HC (g/mi) CO (g/mi) NO (g/mi) 


139 





FIGURE 11.1 


Emissions 


from Diesel 


Powered Cars (1975 FTP). 


Source 


Reference 94 


















































140 


car produces 0.6 g/mi HC. 

Figure 11.1 shows that all of these diesel-powered cars, 

except the Peugeot 504D, can meet the 1975-76 Federal, 1975-76 

California, and 1977 Nationwide Standards for HC, CO and NO . Also, 

all these cars, except the Peugeot 504D, can meet the 1978 Nationwide 

Standards for HC and CO. The problem with these diesel-powered cars 

is in meeting the NO emissions standard of 0.40 g/mi in 1978. 

x 

Some NO controls have been applied to the diesel engine 
x 

and were found to affect the other emissions. 

The control of NO emissions in diesel engines should be made 

x 

during the combustion process. Whereas gasoline engines can employ a 

95 96 

reduction catalyst ’ to control NO , such a technology is not 

x 

effective in diesel engines because of the low level of CO, and the 

presence of a relatively high concentration of oxygen in the exhaust, 

even under full-load conditions. 

Reduction in NO formation during the combustion process is 

achieved by reducing either the maximum temperature reached, the oxygen 

, 97 

concentration, or the residence time. This can be achieved by any 

of the following methods or a combination of them. 

b. Exhaust gas recirculation -- EGR (exhaust gas recirculation) 

is an effective method for the reduction of NO emissions in diesel 

x 

as well as in many other types of combustion engines. It is believed 
that its main effect is to reduce the maximum temperatures by 
increasing the heat capacity of the charge. 

98 

Data reported by Daimler-Benz AG are given in Figure 11.2 
for a speed of 2,400 rpm and two loads. Increasing EGR reduces NO . 

X 

with little effect on HC and CO up to EGR values of 20%,, where NO 

X 

is reduced by about 20% at the low load and 30% at the higher load. 
Increasing EGR above 20% results in an increase in HC and CO emissions. 
The smoke starts to increase at 40% EGR at the light load and 20%, EGR 



141 


i 

o 

CO 

O 

r 

co 


n = 2,400 min 
p Q = 1.8 kp/cm 2 



n = 2,400 min 
P c = 3.6 kp/cm 2 







FIGURE 11.2 Effect of lGR on the Emissions from a Mercedes 
Diesel Engine. 


Source: Reference 98 





























142 


at the higher load. The Daimler-Benz results are for steady-state 
conditions. 

The effects of EGR on the emissions under the 1975 Federal 

99 

Test Procedure (FTP) are reported for an Opel Rekord diesel car, 

and are shown in Figure 11.3. The increase in EGR increases both 

HC and CO emissions above the 1977 standards, while NO is still above 

x 

the 1978 standards of 0.4 g/mi. From this figure, it appears that 
EGR is effective in reducing NO to about 1.0 g/mi, while the HC and 

X 

CO emissions are below the 1977 and 1978 standards of 0.41 and 3.4 
g/mi, respectively. 

Daimler-Benz reported that EGR does not affect power or 
cause fuel penalty at part-load conditions. The effect of EGR on 
durability is still being investigated. 

EGR can be achieved by recycling the exhaust gases from the 
exhaust to the inlet manifolds. Limited EGR is obtained by changing 
the valve overlap. The optimum percentage of EGR required to reduce 
NO^ varies with load. Efforts are being made to optimize the EGR at 
different loads to minimize the penalty in fuel economy and the 
emissions of HC, CO and smoke. 

c. Injection timing -- Retarding the injection is an effective 
way to reduce the NO^ emissions because of its effect on maximum 
temperature and residence time. Retarding the timing also affects 
the HC and CO emissions. Results reported by Opel on the Opel Rekord 

diesel car, using the 1975 FTP are shown in Figure 11.4. By retarding 

o o 

the static injection from 6 BTDC (before top dead center) to 1.5 

BTDC, NO emissions dropped by 307 o (from 2.47 g/mi to 1.73 g/mi), 

X 

while the HC and CO emissions increased by 447, and 33%, respectively. 

Results obtained from Perkinsgiven in Table 11.2, show 
the effect of retarding the injection timing by 4° with respect to 
the standard timing of 21° before top dead center. 



143 



FIGURE 11.3 Effect of EGR on Opel Rekord Diesel Car (1975 FTP). 


Source: Reference 99 


NO (g/mi) 































144 




FIGURE 11.4 


Source: Reference 99 








145 


TABLE 11.2 

Effect of Injection Timing on Emissions from Perkins 154 Engine 

in Ford Zephyr Car (CVS Cycle) 

Standing Timing Retarded Timing % Change 



21 BTCD 
g/mi 

17 BTDC 
g/mi 



HC 

0.46 

0.66 

+ 

43% 

CO 

2.79 

3.78 

+ 

35% 

NO 

X 

2.33 

1.73 

- 

26% 

REF. 100 


Perkins reports that the change in fuel economy caused by 

this injection retard is within + 67 0 (which is their production 

tolerance), and that there has been no problem in meeting the smoke 

levels regulated by the European governments. 

Retarding the injection is effective in reducing NO , but 

x 

causes an increase in HC and CO. The 1978 emissions standards cannot 
be achieved by diesel-powered cars by using either injection retard 
or a combination of injection retard and EGR. 

d. Other controls -- Other techniques used to reduce the NO 

101 x 

emissions are control of the air/fuel ratio at light loads, use of 

97 

water injection, use of fuel additives (Ref. 98 p. 749), use of 
low compression ratios together with supercharging, and modifications 
in the fuel-injection system and combustion-chamber design. 

e. Summary -- In summary, the automotive diesel engine 

manufacturers are uncertain that they can meet the 0.40 g/mi standard 

for NO in the future, even in an experimental engine. They feel 
x 

that the diesel engine can meet a level of NO = 1.5-2.0 g/mi with 

X 

little changes in the design of current production engines, without 
any penalty in fuel economy. Ricardo and Co. Engineers, in a recent 




146 


report to EPA, “ indicated that a conventional, naturally aspirated 
swirl-chamber diesel engine, in a 3,500 lb vehicle, should be able to 
achieve HC = 0.41 g/mi, CO = 3.4 g/mi and NO = 1.5 g/mi. Some EGR 
may be necessary to ensure a sufficient margin for production tolerances. 

It is anticipated that levels of NO^ equal to 1.0 g/mi, or 
even as low as 0.6 g/mi, might be reached in the future if sufficient 
research is made to optimize all the NO^ control techniques. 

11.3 Nonregulated Emissions 

The nonregulated emissions studies in this Section are: 
particulates, benzo (a) pyrine, sulfur dioxide, sulfuric acid, 
aldehydes and ammonia. Many of these nonregulated pollutants are 
as harmful or even more harmful than the three regulated species. It 
is expected that some of these undesirable species will be regulated 
in the future. 

a. Particulates — Particulates from diesel engines appear as 
blue and white smoke under cold-running conditions and low loads, and 
as black smoke near full-load operation. The blue and white smoke 
contains unburned and partially oxidized fuel, and the black smoke 
is mainly carbon. 

93 

Figure 11.5 shows the airborne particulate emissions in 
grams per mile on the 1975 FTP from three diesel powered cars, two 
American 1975 gasoline-powered cars, and a PROCO-Capri car. The two 
gasoline cars are equipped with catalytic converters. In one of the 
gasoline cars, the aged catalyst increased the particulate emissions 
by 2677o. The PROCO-Capri car produced more particulates than the 
gasoline cars. The diesels produced the highest concentration of 
particulate emissions. 

The proposed level of 0.1 g/mi over the constant-volume¬ 
sampling cycle during the federal testing procedure is difficult to 
achieve by the diesel engine. A proposed method to reduce particulate 




AIRBORNE PARTICULATE, 75 FTP (g/mi) 


147 



FIGURE 11.5 Airborne 
Powered Cars. 


Particulates Emitted from Diesel and 


Gasoline 


Source 


Reference 93 


Ford t Aged Catalyst i Air 







































148 


emissions is a soot filter (non-catalytic) which would hold soot 
particles emitted at part loads and burn them at high loads when the 
exhaust temperatures are high enough to cause their oxidation. 

b. Benzo(a)pyrine -- Benzo(a)pyrine (BAP) is an undesirable 
carcinogenic species emitted from combustion engines. Among the 
factors which affect its concentration in the engine exhaust is the 
concentration of aromatics in the fuel. Without adding tetraethyllead 
to the gasoline, the concentration of the aromatic compounds in the 
fuel has to be increased to arrive at a fuel with a reasonable octane 
number and combustion characteristics. This might result in an 
increase in BAP emissions in the gasoline engine exhaust in the future. 

A comparison between the BAP emissions in three diesel-cars 

and for gasoline cars is shown in Figure 11.6 for 1975 FTP cold start, 

103 

and in Figure 11.7 for 60-mph, steady-state conditions. 

BAP emissions in the diesel exhaust are fairly low under 
combined cold starting and 60-mph, steady running if compared with 
the gasoline engine. The diesel-engine BAP emissions are of the same 
order of magnitude as the stratified-charge engines. 

The above observations are for a limited number of vehicles; 
additional data covering a larger number of vehicles are needed to 
study the BAP emissions from different types of automotive engines. 

c. Sulfur compounds -- The concentration of the sulfur compounds 

in the exhaust is directly related to the sulfur content of the fuel. 

The Federal Register specifies the sulfur content to be 0.057,-0.20% 

for type 1-D and 0.27,-0.57, for type 2-D diesel fuel and less than 0.17, 

for gasoline. Figure 11.8 shows the sulfur dioxide and sulfuric acid 

mass emissions in grams per mile for two gasoline-and one diesel- 

93 

powered car, and the percent of sulfur converted to H^SO^. The 

tests are at 60 mph, steady-state running conditions. The H^SO^ mass 
emissions are almost the same for the diesel and gasoline engines, in 





BENZO[a| PYRENE (BAP) (ppm) 


149 




FIGURE 11.6 Benzo(a)Pyrene Emissions from Different 
Automotive Engines, According to 1975 FTP-Cold Start. 


Source: Reference 103 






















150 


3601— 


320 


280 


S 240 

Q_ 

< 

CO 


UJ 

Z 

LU 

QC 

> 

CL 

"co 

o 

N 

Z 

UJ 

CQ 


200 


160 


120 


80 


40 


0 


Diesel: 


Gasoline: 


Stratified 

Charge: 


n 


1. 

2 . 

3. 

1. 

2 . 

3. 

4. 

1. 

2 . 


Mercedes 

Opel 

Peugeot 

72 Pontiac 
+ Catalyst + Air 
Ford 

(.41,3.4, 3.1) 

72 Ford 

+ Fresh Catalyst + Air 
72 Ford 

+ Aged Catalyst + Air 

Cricket TCCS 
74 Ford Capri Proco 


-O-JZ] 


<D 

t/3 

0) 


a> 

c 

o 

t/3 

oo 


TJ 

cu 


to 


03 

03 


CO 
£ -C 
CO O 


FIGURE 11.7 Benzo(a)Pyrene Emissions from Different 
Automotive Engines at 60 mph Steady Running Conditions. 

Source: Reference 103 












151 




UJ 


cc 

UJ 

> 

z 

o 

o 


co 




LU 

o 

cc 

UJ 

Q. 



FIGURE 11.8 Sulfur Compounds Emissions from 
Different Cars. 


Source: Reference 93 



























152 


spite of the fact that the sulfur content of the diesel fuel used in 
these tests was 10 times that of gasoline. The SO^ emissions in 
diesel exhaust are about three or four times that of the gasoline 
exhaust. 

The control of S0„ and H SO. emissions in the diesel exhaust 

2 2 4 

can be achieved in the refinery by reducing the sulfur content of the 
fuel. This may cause an increase in the fuel cost. 


d. Aldehydes — The aldehydes are partially oxidized hydrocarbons 
and are mainly formaldehyde. Other aldehydes emitted from combustion 
systems are higher aliphatic aldehydes, aromatic aldehydes, and 
aliphatic ketones. 

All of the results in this Section are reported as |g^malde- 
hyde HCHo!^ The aldehyde emissions are given in Table 11.3 for 
two cars equipped with diesel engines, two with models of Wankel 

engines, four with gasoline engines, two with stratified-charge 

103 

engines, and one with a gas turbine. The results are for the 
emissions during 43 minutes of the Modified Federal Cycle Cold Start 
(MFCCS) and one-hour, steady-state, 60-mph hot start. The results 
for the Honda and Opel Diesel (reports 1 and 2 in Table 11.3) are for 
the original Federal Cycle Cold Start. The MFCCS aldehydes are 
plotted for the Peugeot and other cars in Figure 11.9. It is noticed 
that the cars powered with engines using a heterogeneous mixture 
(except for Ford PR0C0) produce higher aldehyde emissions. The Ford 
PR0C0 car is equipped with a catalytic converter. 

The aldehyde emissions under the steady-state, 60-mph test, 
are shown in Figure 11.10. 

The contribution of the aldehydes to air pollution should 

not be overlooked since their specific reactivity is higher than many 

105 

unburned hydrocarbons in photochemical smog formation. Also, their 

effect on health and plant damage is worse than many unburned 
hydrocarbons. 



153 


TABLE 11.3 

Aldehydes and Amnonia Emissions from Different Types of Cars 




HCHO 

PPM 



NHo 

PPM 

Report 

No. 

Vehicle 

MFCCS 

60 mph 

S.S. 

MFCCS 

60 mph 

S.S. 

1* 

Honda Prototype 

Civic CVCC engine 

1.7 

64.5 

3.5 

9 

2* 

1973 Opel Diesel 

17.5 

18.5 

19.4 

38.9 

3 

Peugeot, 4 Sp. trans., 
Diesel Fuel #2 

602.5 

253.9 

11.1 

7.28 

4 

RX2 Mazda D1527 
(Thermal Reactor and 

924.6 

2,341.6 

8.8 

32.9 

5 

a reactor by-pass) air 
pump and EGR 

EPA Williams Gas Turbine 

349.1 

80.53 

15.14 

28.20 

6 

Yellow Mazda RX3 
(Equipped as in Rep. #4) 

381.6 

(50 mph) 

1,541.3 

9.32 

89.37 

7 

72 EPA Ford, durability 
Catalyst, Veh. 24A51 

14.67 

3.1 

3.37 

0.88 

8 

72 EPA Ford, SLAVE 

Catalyst, Veh. 24A51 

74.04 

26.29 

2.52 

0.75 

9 

Mazda D1527 RX2 Silver 
(Equipped as in Rep. #4) 

862.9 

1,385.1 

5.81 

32.5 

10 

Pontiac 1972 GM 2477 
with 1975 hardware with 

21.41 

23.3 

20.7 

17.35 

11 

30,768 miles 

Yellow Mazda RX3 
(Equipped as in Rep. #4) 

345.56 

1,479.8 

10.9 

36 

12 

EPA Ford, 1973, A 342-25 
(designed for HC = 0.41, 

71.67 

149.83 

25.31 

7.28 

13 

CO = 3.4 and NO =3.1) 

X 

Mazda RX3 

(Equipped as in Rep. #4) 

592.9 

1,564.1 

14.03 

36.5 

14 

1974 Ford Capri EPA 0191 
(PROCO) 

38.86 

31.46 

6.53 

13.67 

15 

EPA CRICKET TCCS #8 
(with catalytic converter) 

524.6 

181.9 

1.72 

1.29 

16 

EPA CRICKET TCCS 

(with catalytic converter) 

805.2 

204.1 

1.32 

.57 

17 

Mazda RX3 7,226.0 miles 

665.7 


5.74 



-'Reports 1 and 2 were on the original federal cycle cold start. 


REF 103 











HCHO (ppm) 


154 


1,000 


o 

CD 

800 


CT) 

D 

0) 

Q_ 

600 



400 




200 

100 

80 

60 

40 

20 

10 

8 

6 


< 

+ 



< 

+ 

t/J 

> 

CD 

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03 

O 

■Q 

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O) 

< 

+ 

“D 

i- 

O 


CM 

r^ 


co 

CJ 

O 


03 

u 

v_ 

O 


B 


A 


FIGURE 11.9 HCHO Emissions for the Modified 
Federal Cycle Cold Start (MFCCS). 


Source: Reference ]03 


] 74 Ford Capri Proco 





















HCHO (ppm) 


155 


1,000 

800 

600 


400 

200 

100 

80 

60 

40 

20 

10 

8 

6 

4 


1 


o 

o 

a> 

3 

e 

Q. 


n 

ro 

o 

T3 

k- 

o 


> 

TO 

TO 

o 


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.2 

c 

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Q. 

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+ 

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TO 

TO 

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LI¬ 

M¬ 

'D 

- 

o 

LL 

CM 

r^ 


TO 

o 

*D 

TO 

05 

< 


*o 

— 

o 


CM 


FIGURE 11.10 
Conditions. 


HCHO for 60 mph Steady Running 


Source: Reference 103 


] Cricket TCCS 
□ 74 Ford Capri Proco 


















156 


e. Ammonia emissions — The NH„ emissions from the diesel and 

J 103 

other engines are shown in Table 11.3. It is noticed that NH^ 

is emitted from all the combustion engines. A conclusion for the NH. 
characteristics of each engine is difficult to make at this stage, 
because of the limited amount of experimental data. 


11.4 Fuel Economy 

The better fuel economy of the diesel engine over the gasoline 
engine is the result of its higher compression ratios, higher air/fuel 
ratios, and the absence of the throttle valve for load control in the 
diesel. Accordingly, the superior fuel economy of the diesel is at 
part loads. 

The following figures show comparative economy results for diesel- 
and gasoline-powered cars, in many application. Figure 11.11 shows 
the results submitted by Daimler-Benz (Ref.98 p. 769) for the miles 
per gallon of the MB220D diesel and the 1975 MB230 gasoline engine 
under steady-state conditions and at speeds up to 75 mph. Both cars 
have an I.W. = 3,500 lbs. The savings in fuel consumption in the 
diesel car varies from 537, at 30 mph to 327 0 at 70 mph. Under the CVS 
test, the MB220 diesel averages 23.6 mpg as compared to 13.9-17.2 mpg 
for the 1975 gasoline engine; i.e., an average saving of 277, to 417, 
in fuel consumption. Recent results obtained from EPA Ann Arbor 
show that the 1975 MB240D diesel car averages 23 mpg, which makes it 
as economical as the MB220D. 

It should be noted that part of the fuel saving in the above 

comparison is caused by the lower horsepower of the diesel engine as 

99 

compared to the gasoline engine. A comparison by Opel, based on 
engines of equal power output fitted in the same car, is given in 
Table 11.4. 




157 



SPEED (mph) 

FIGURE 11.11 Comparison of Fuel Economy at Road Load for Mercedes Diesel 
and Gasoline Cars’. 


Source: Reference 98 






TABLE 11.4 


Comparison Between Opel Diesel and Gasoline Cars 



Diesel Car 

Gasoline Car 

Car Weight, lbs 

3,070 

2,750 

Engine Displacement, CC 

2^10 

1,618 

Miles Per Gallon 

(mixed-duty cycle) 

34 

27 

Saving 

21% 

REF. 99 

A similar comparison based 

on equal power 

B . 108 

is reported by Peugeot 


on their 504 diesel and 404 gasoline engines. Here the average 

saving in fuel consumption is 26%. 

109 

A comparison between two foreign diesel cars and an American 
car, all having the same weight (3,000 lb), is shown in Figure 11.12 
for steady-state operation and in Figure 11.13 for city, suburban, and 
average-driving conditions. Here the average saving in fuel consumption 
is 367o for the two diesel-powered cars. It should be noted that a part 
of this saving is caused by the use of manual transmissions in the 
diesel cars as compared to an automatic transmission in the gasoline 
car. 

The saving in fuel consumption in taxi application in two 

110 

European cities is shown in Table 11.5. 





50 

45 

40 

35 

30 

25 

20 

15 

10 

5 

m 

1 . 


159 


73 Peugeot 
4 Speed.M T 



J_I_I_L 

30 40 50 60 


J 

70 


SPEED (mph) 

Comparison of mpg for Different Cars Under Steady State 


109 




160 



30 


20 - 


10 


Average 


-O 



CD 



0) 


■o 

CL 


ID 

CO 

“O 

CD 

'S’ 

CD 

CD 

CL 

CO 

"O 

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l*: _ 

a 

^ — 

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CD O 

4- O 

a> o 

cr o 

o o 

c o 

o 

<D O 

CT - 

2 o 

a £2 

D 00 

CD ’ — ’ 

3 «2 

o H 

a_ (_ 

s (— 

00 

00 ^ 
f"* «> 

E < 


FIGURE 11.13 Comparison of mpg for Different Cars 
Under City, Suburban and Average Driving Conditions. 


Source: Reference 109 
























161 


TABLE 11.5 


Fuel Economy in Taxi Application 


Miles per gallon 


Diesel 


Gasoline 


Saving 


London Taxi 

30.6 

15.9 

48% 

Paris Taxi 

31.4 

21.7 

31% 


REF. 110 

Similar savings in fuel consumption have been reported by replacing 
the gasoline engine with a diesel engine in U.S. Post Office one-half, 

one-and five-ton vehicles'^'*’ and in vans equipped with Perkins 
a- i • 100 

diesel engines. 

Part of the higher miles per gallon for the diesel-powered 
car is caused by the higher energy content of one gallon of diesel 
fuel as compared to the same volume of gasoline, as shown in Table 11.6 
(Ref.98 , p. 850). 


TABLE 11.6 


Comparison 

Between Diesel 

and Gasoline Fuels 


Average mass 

Average BTU 

Fuel 

per gallon 

per gallon 

Diesel 

7.1 

137,750 

Gasoline 

6.0 

123,500 


REF. 98 

The increase in the energy content of one gallon of diesel fuel is 
12% above that of gasoline. 











162 


From a total energy point of view, the energy expenditure in 
producing the fuel at the refinery should be taken into consideration. 
Diesel engines can use a wide range of distillates which are produced 
at a lower cost than gasoline. 

In summary, the average saving in fuel consumption by using the 
diesel engine instead of the gasoline engine in passenger cars varies 
between 25% to 50%. 


11.5 Initial and Maintenance Costs 


Diesel engines initially cost about 50% more than gasoline 

engines. Half of this difference is attributed to the high cost of 

102 

the fuel-injection system, and is partially caused by its limited 

112 

mass production. For a diesel engine to have the same power as a 

gasoline engine, it should have a larger displacement volume, since 

the air utilization is less. Also, it should have heavier parts to 

stand the much higher gas pressures produced in the cylinder as a 

result of the higher compression ratio used. These, too, increase 

production costs of the engine. The heavier starting motors and 

batteries required to overcome the high compression pressures and to 

the production cost of the diesel-powered cars. 

However, the maintenance cost for the diesel engine is lower 

than that for the gasoline engine. The injection system does not 

require the frequent maintenance and replacement of parts experienced 

with the ignition system and carburetor of the gasoline engine, 

although there is a slightly higher cost for each service. On the 

other hand, routine maintenance (oil and filter change) is more 

frequent for the diesel engine. 

Daimler-Benz reported the initial and maintenance costs for 

113 

their MB 1975 gasoline and diesel cars. These costs are given in 

Table 11.7. The maintenance cost includes general maintenance (spark 



163 

TABLE 11.7 


Initial and Maintenance Costs and Perfomance 
of Mercedes 1975 Cars * 


Diesel Gasoline 

24OD 2.3L 


California 

Federal 

Model 

Model 


Vehicle Weight, lb 

3,500 

3,200 

3,200 

Horsepower 

65 

95 

95 

Weight-Power Ratio 

Ib/HP 

6.8 

2.6 

2.6 

Fuel Economy 
mpg 

21-22 

16.2 

15.5 

Acceleration time, sec 

60 mpg 

24.6 

13.7 

13.7 

Initial Cost 




Maintenance Cost for 
100,000 miles 

$1,153 

$2,590 

$2,590 

Initial Price 

(1974 Model) 

$8,715 

$8 420 

$8,420 

Total Cost for 

100,000 miles 
(assuming 1974 

Model Prices) 

$9,868 

$11,010 

$11,010 


*The initial cost for the Mercedes 1975 cars had not been 
announced by the company at the time of writing this report. 

The initial prices for the 1974 models are used for comparison. 


REF 113 





164 


plugs, tuning, oil changes, etc.) and two catalyst changes for the 
gasoline car. The larger cost differential between the two cars in 
1975 is the high cost for the catalyst change which was quoted at $600 
for this six-cylinder and $800 for the eight-cylinder gasoline engine. 
The 1974 maintenance costs are $1,132 for the diesel and $1,062 for 
the gasoline engine. 

At 23 mpg for the 1975 diesel car and 16 mpg for the 1975 
gasoline car, and at 45q/gal for the diesel fuel and 55q/gal for 
gasoline, the fuel cost for 100,000 miles would be $1,957 and $3,438 
for the diesel and gasoline cars, respectively. For the sake of 
comparison, considering 1974 model prices, the estimated total initial 
maintenance and fuel costs are $11,825 for the diesel and $14,448 for 
the gasoline car. This means a saving of 187, to the owner of the 
diesel-powered car. 

The superior economy of the diesel-powered car over the gasoline- 
powered car is manifested in applications involving part-load operations. 
For example, taxicab fleet owners in London and other cities in Europe 
had to shift from the gasoline to the diesel engines to make a profit 
while keeping the fares within the limits imposed by the local 
authorities. 

Diesel engines proved to be economical in taxicab fleet 
operations even in countries where the price of the diesel fuel is 
equal to or slightly higher than gasoline fuel, such as in Great 
Britain. In other countries where diesel fuel is less expensive than 
gasoline, the savings increase proportionally. 

The present higher initial cost of the diesel-powered car over 
the gasoline car is expected to diminish in the 1975 model cars and 
those that follow. For 1975 California cars and 1977 nationwide cars, 
the gasoline-powered cars should be equipped with catalytic converters 
and feedback systems. Some of the gasoline engines will be equipped 
with fuel-injection equipment. All these add-on devices will increase 


165 


the initial and maintenance costs of the gasoline-powered cars and make 
the diesel-powered car more economical. 

11.6 Driveability -- The driveability of two Mercedes diesel 

automatic transmission (A/T) vehicles (1969 and 1974 models), a 1973 

manual transmission (M/T) Opel Rekord and a 1973 M/T Peugeot were 

compared to the driveability of a 1973 Pinto and a Honda A/T CVCC 
109 

vehicle. The results are shown in Figure 11.14. The A/T diesels 
were better than the one A/T gasoline engine in the following three 
types of evaluation: minimum driving ratings, drive ratings average, 
and the idel quality rating. The M/T diesels were better than the 
Honda CVCC M/T in two categories. However, the Honda CVCC M/T was 
better in idle quality. Daimler-Benz reported that the driveability 
of their diesel-powered vehicle is the same as their gasoline-powered 
vehicle. 

11.7 Intrinsic Problem Areas 

a. Starting -- Automotive diesel engines which can meet the 
emissions standards have a prechamber (Mercedes) or swirl-type 
(Peugeot and Opel) combustion chamber. These types of combustion 
chambers need a starting aid in the form of a glow plug. Because 
the glow plug should reach a high temperature before cranking the 
engine, some delay in starting is experienced. At present, research 
is being done on a high-intensity glow plug to reduce starting delay. 

b. Noise -- The diesel engine is inherently noisier than the 
gasoline engine, particularly after cold start and during idling. This 
will be discussed under the noise emission classifications of exterior 
and interior noise. 

Figure 11.15 shows a comparison made by the Ford Motor 
Company between the exterior noise levels of three diesel-powered cars 






IDLE QUALITY AVERAGE DRIVING MINIMUM DRIVING 


166 





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FIGURE 11.14 Comparative Drivability of Diesel Powered 
and Other Cars. 


Source: Reference 109 


1/I/M 










































167 



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FIGURE 11.15 Exterior Noise Levels from Different Cars. 


Source 


Reference 109 














168 


109 

and three American gasoline-powered cars. This comparison is 

according to the SAE Standard J 986a test procedures.* This test 
calls for a wide-open throttle acceleration from 30 mph to maximum 
engine revolutions-per-minute over a distance of 100 ft, with a 
microphone stationed 40-50 ft away. The results show that the three 
diesel engines have lower sound levels than the 1974 Torino and have 
the same sound level as the 1974 Pinto. Also, these engines meet 
the present California standards, and those proposed for 1975. The 
1973 Peugeot meets the proposed 1978 California standards. The 1969 
Mercedes and the 1973 Opel are 0.5 dB above the proposed 1978 California 
standards. 

Recent comparative noise results reported by Southwest 
94 

Research Institute are shown in Figure 11.16 and Table 11.8 for 
cars of different makes. Figure 11.16 indicates that some diesel- 
powered cars produced less exterior noise than the gasoline-powered 
car and others produced more noise. Also, the diesel-powered cars, 
except the Mercedes, meet the proposed 1978 California noise standards 
of 75 dbA. The Mercedes car exceeds the proposed 1978 California 
standards by 2 dbA, and the Capri PROCO exceeds these standards by 
dbA. 

A comparison between diesel-and gasoline-powered cars of 
the same make are shown in Figure 11.17. The noise levels of the 
Mercedes 220D diesel and 220 gasoline cars are shown in Figure 11.17 
for different driving modes (Ref. 98, p. 773). The diesel produces 
noise levels of 1 dbA to 5 dbA higher than the gasoline engines. The 
diesel car is particularly noisy during engine start up and idling. 

The noise levels of the Peugeot 504 diesel car are higher than the 


*SAE -- Society of Automotive Engineers 



169 



FIGURE 11.16 Exterior Noise Levels from Different Cars. 


Source 


Reference 94 


Capri Proco 


















170 


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(V)aP'03A31 3SI0N UOIU31X3 


FIGURE 11.17 Comparison of Exterior Noise Levels for 2.2 Liter 
Mercedes Gasoline and Diesel Cars. 








































Comparison Between Exterior and Interior Noise Levels of 
Diesel-and-Gasoline-Powered Cars 


171 




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172 


Peugeot 504 gasoline car by 4 dbA during idling and 2 dbA at 31 mph. 
The two cars have equal noise levels at 50 mph and 62 mph. At 74 mph, 
the diesel car is noisier by 2 dbA, (Ref. 98, p. 839). 

Table 11.8 also shows the results of many tests conducted 

by Southwest Research Institute according to the Federal Clean Car 

94 

Incentive Program. These results also show that the exterior drive 
by and idle noise for the diesel cars is higher than the gasoline 
powered cars. 

109 

A comparison between the steady-state interior noise 
levels (A-weighted-dbA) of three diesel vehicles and those of a 1974 
Torino and a 1974 Pinto 2.3L are shown in Figure 11.18 for speeds 
ranging from 20 mph to 60 mph on a smooth asphalt road. The results 
show that the Torino is fairly quiet compared to the diesels, but that 
the Pinto has nearly the same noise levels. 

It should be noted that the interior noise depends to a 
great extent on the packaging of the engines, the structure of the 
car, interior design and blower noise. 

Table 11.8 shows that some diesel cars have lower interior 
noise levels than gasoline cars and that this noise level depends on 
whether the blower is on or off. 

The noise level of diesel engines may be reduced by 
modifications to the fuel injection system, changes in injection 
timing, use of pilot injection, structural changes, basic changes in 
engine design (such as using more cylinder of smaller bore, etc.), 
intake and exhaust-manifold modifications, and engine isolation 
techniques. 

c. Odor -- The odor produced by the diesel engine is caused by 
products of the auto-ignition process. Even gasoline engines produce 
odor if they run on or "diesel". 

Little research work has been done to define which of the 
stages of the auto-ignition process produce the characteristic odor. 



173 



SPEED (mph) 

FIGURE 11.18 Interior Noise Levels from Different Cars. 


Source: Reference 109 




174 


One research program, using n-heptane-air mixtures, in a motored CFR 

engine, indicated that odor is the result of quenching the second stage 

97 94 

(cool flame) in the auto-ignition process. Table 11.9 shows 
the results of a comparison of the exhaust odor from four diesel - 
powered cars, two gasoline cars and a PROCO Capri car. These exhaust- 
odor results are for 10 driving modes covering the whole range of 
loads and speeds. The averages of all 10 modes show that the odor 
from the diesel cars is, in general, higher than that from the gasoline 
or PROCO cars. 

The use of exhaust-catalytic converters to reduce odor, 

114 

and other incomplete combustion products in the diesel exhaust, is 

still in the research stage. It is not expected that it will be 
applied to the actual engine in the near future. 

Further basic research is needed to study odor control. 

d. Low power-weight ratio -- The diesel engine produces less 
power than the gasoline engine of equal displacement, for two reasons. 
First, the overall fuel/air ratio in the diesel is always leaner 
than the stoichiometric ratio. The limit to the increase in fuel/air 
ratio is smoke production. Second, the maximum rated speeds in 
diesel engines are less than in gasoline engines. The limit here is 
the short time allowed for fuel injection, evaporation, mixing and 
combustion for proper engine operation. Mechanical-stress considerations 
also limit the speed of the diesel engine. 

The low power/weight ratio causes the diesel-powered car to 
take a longer time for acceleration. Table 11.7 shows that time for 
acceleration from 0 to 60 mph is 13.7 seconds for the Mercedes 2.3L 
gasoline engine, and 24.6 seconds for the 240D diesel car. For the 
Peugeot 504 diesel this time is 23.6 seconds, and it is 16.2 seconds 
for the 504 Peugeot gasoline engine. 



175 

TABLE 11.9 

Comparison of Odor from Diesel-and Gasoline-Powered Cars 


Type 

Fuel 

Car 

Six Steady- 
States 

Idle 

Three 
Trans. 

All Ten 
Conditions 

Diesel 

Datsun-Nissan W 

3.4 

2.9 

4.7 

3.8 


S 

3.2 

2.7 

4.6 

3.6 


Mercedes 220D 

3.0 

3.1 

3.7 

3.2 


Peugeot 504D 

5.2 

4.8 

5.7 

5.3 


Opel Rekord 

3.9 

3.3 

4.1 

3.9 

Gasoline 

Ford LTD 

1.5 

1.2 

1.5 

0.6 


Standard Capri 

3.0 

3.3 

2.9 

3.0 


PROCO Capri 

1.0 

0.7 

1.6 

1.1 

REF 94 








176 


Turbocharging is an effective tool for improving the power/ 
weight ratio of the diesel engine. Turbocharging increases the 
maximum power, torque and rated speed of the engine. This improves 
the acceleration characteristics of the vehicle. The effect of 
turbocharging on fuel economy and emissions from the diesel-powered 
car is presently being studied by many manufacturers. The present 
attempts are being made by adding a turbocharger to existing diesel 
engines without lowering their compression ratio or optimizing the 
injection and combustion processes. The results of these attempts 
are not conclusive. The penalty in fuel economy at idling and low 
loads as a result of turbocharging depends on the design of the intake 
and exhaust systems and the degree of matching the turbocharger to the 
engine. The effect of turbocharging on the emissions during a FTP 
cycle has not been assessed. 

11.8 Conclusions 

a. Technological feasibility of meeting the different emission 

standards : 

(,1) Diesel engines, currently mass-produced to power 

passenger cars of 3,000 lb to 3,500 lb, can meet the 
19~7 standards without EGR, add-on exhaust treatment 
or feedback systems. 

(2) There is no penalty in the initial cost, maintenance 
cost, or fuel economy of these engines in meeting 
these standards. 

(3) These diesel engines proved to be the most economical 
power plants as far as fuel consumption is concerned 
and are as reliable and durable in the field as the 
non-controlled gasoline engine. 





177 


(4) The total cost to the owner for one of these mass- 
produced 1975 cars, including initial, maintenance and 
fuel cost for 100,000 miles, will be less than that for 
the equivalent gasoline-engine car. 

(5) No extraordinary maintenance is required in the field 
during the useful life of the vehicle due to the absence 
of catalytic converters and feedback systems and the 
high durability of the diesel engine. 

b. 1978 Nationwide standards 

(1) Based on the presently known technology, it is not 

feasible for the diesel-powered car to meet the 1978 

NO standards of 0.4 g/mi. 
x 

(2) If the NO standard is relaxed to 1.5-2 g/mi, many 

X 

currently mass-produced, diesel-powered cars would be 
able to meet the standard without any penalty in initial, 
maintenance or fuel cost. Thus, the diesel-powered 
car would be superior to the gasoline version in total 
cost to the customer, and in reliability and durability. 

(3) With the application of EGR, injection-system modification 
and injection retard, it may be possible for currently 
produced diesel-powered cars to meet NO^ levels of 

1.0 g/mi., but this may result in a penalty of 57 0 to 
15% in fuel economy and power. The effect on 
durability of the engine has not been assessed. 

(4) Levels of NO , slightly less than 1.0 g/mi (but not less 

X 

than 0.6 g/mi) might be reached by diesel-powered cars 
if sufficient research is conducted to optimize all the 
NO^-control techniques. 



178 


c. Problem areas 

(1) Intrinsic problem areas in the diesel powered cars 
which deserve further research are: particulates, 
odor, noise, and low power/weight ratio. 

(2) The future standards for the nonregulated emissions 
should of course, take into consideration the harmful 
effect of the pollutants rather than the total mass 
of the emissions. For example, one gram of aldehydes 
may be more harmful to the health and environment 
than one gram of paraffinic hydrocarbons. Also, the 
total mass of the particulate emissions may be high 
in the exhaust of one type of engine, but the mass of 
harmful species (such as BAP) may be low. 

The relaxation of 1978 NO emissions should be decided 

x 

on as soon as possible. The lead time needed for 
manufacturing is on the order of five years. 


( 3 ) 



12. ALTERNATIVE POWER PLANTS FOR AUTOMOBILES 


12.1 Introduction 

Activities in alternative power-plant development for automobiles 
have continued in the two years since Reference 116 was written. Many 
of the problem areas have been more firmly stated and some of the less 
applicable power plants have been weeded out. The engine characteristics 
and development times have become more firm. It is clear that there are 
no high-performance alternative power plants that can go into mass pro¬ 
duction before the 1980's. 

Alternative heat engines in their major forms are gas turbines, 
Stirling engines, and Rankine engines. These can be categorized as 
continuous-combustion engines in which a fire is established and heat 
is continuously supplied to the system until power is no longer needed. 
There are a number of other engines that fit into the spectrum repre¬ 
sented by these three major types, such as several forms of reciprocating 
Brayton-cycle engines and super-critical-fluid Rankine cycles. In this 
Section, concentration will be with the major types. These heat engines 
can use energy stored in the form of liquid or gaseous fuel. Also, the 
Stirling and Rankine engines can use energy stored in any fuel and in 
the form of heat. 

Storage batteries have been used extensively for over a century, 
and these can be used in modified form for powering automobiles without 
the aid of heat engines. Also, flywheels have been used for over a 
century, but more recently they have been used to supply power to the 
drive wheels of busses. With the use of new materials and recent 
technology, high-performance flywheels can now be designed to be used 
directly, or as a mechanical energy-storage system for powering an 
electrical drive for automobiles. 

Hybrid systems are combinations of two or more different kinds 
of power plants or of different versions of similar power plants. The 
aim of hybrids is to allow the complete system to perform according 
to the best features of each part. Those hybrids that have 


179 



180 


been given the most attention in the last few years are battery-heat 
engine combinations. Some consideration has also been given to 
combining two different kinds of batteries in an electrical drive 
system. 

Alternative engines for automobiles are in an embryo state of 
development. While gas turbines, Stirling engines, steam engines, 
advanced lead-acid battery power plants, and electric-heat engine 
hybrids have been running in automobiles, there are none that can be 
considered as suitable prototypes for manufacture. That is, the 
developers themselves have indicated that at least another generation 
of development is required before they will be satisfied that their 
particular power plant has demonstrated its full technical, economic 
and customer-satisfaction potential. There are no flywheel or 
flywheel-hybrid power plants presently operating in automobiles; 
and there are no high-performance, battery-powered systems running 
in automobiles. 

A few examples of experimental continuous-combustion engines 
have progressed beyond the dynomometer testing stage and are presently 
mounted in automobiles that are either available, or very nearly 
will be available, for test driving. These include two Stirling 
engines (United Stirling and Philips), three gas turbines (Williams 
Research and Volkswagen, Chrysler, and General Motors), and eight 
Rankine engines (Carter, Scientific Energy Systems, Steam Power Systems, 
Pritchard, Thermo-Electron, Aerojet, Kinetics Corp., and Williams 
Brothers). Other cars, such as GM's steam cars and Rover's gas- 
turbine car, have operated in the past but their development is now 
dormant. Others, such as the Paxve Rankine engine car, are in a 
temporary state of dormancy. All of the active engine programs 
whose goal is mass application to automobiles are aimed at 
demonstration and upgrading. Measured performance and engine 
characteristics that are considered as the final state of 


181 


development do not exist. Therefore, while some data and 
quantitative characteristics are reported herein, they are not to be 
considered as representative of fully developed engines. Most of 
the information is, per force, tempered by judgment of the source 
and of the panel of consultants; the conclusions stated throughout 
this Section are judgments of the latter. 

Similar judgment has been rendered in some cases concerning 
batteries and electric drives. This is particularly true for the 
high-performance batteries still under development. Also, the 
electric drive situation is in a state of flux with final choice of 
system not made in most cases. 

12.2 Gas Turbine 

In comparison with aircraft and industrial gas turbines, the 
automotive gas turbine has a much more difficult job and has 
necessitated considerable development effort. Efficiency, low 
idle fuel consumption, good off-design performance, and fast response 
requirements have forced the developers to turn their attention to 
higher turbine inlet temperatures, simple yet efficient rotating 
components and highly effective regenerators. Thrust is not needed 
as in jet engines. Steady load as in industrial gas turbines is the 
antithesis of automotive gas turbine use. These aspects make the 
automotive gas turbine unique. 

General Motors demonstrated attainment of 1978 emissions 
122 

standards in 1974. It used an existing engine (GT 225) in an 
automobile weighing 5,000 lb, running through the federal driving 
cycle on chassis rolls. A large variable-geometry combustion was 
fitted and was manually controlled from an off-vehicle console. All 
four tests made were reported as being below the 1977 limits: 



182 


HC CO 

grams per mile 

0.02 2.7 


NOx 


0.32 


from cold starts using diesel fuels. Other developments also show 
123-128 

low emissions. Above 2.0 g/mi NO a fixed combustion geometry can 

X 

be used. Achievement of NO as low as 0.4 g/mi requires variable geome- 

x 125126 

try, although the Zwick combustion ’ uses only a very simple flow- 
splitter concept. This combustion was tested on a small gas turbine and 
yielded the following emissions (translated from g/kg): 


HC 

CO 

grams per mile 

N0 X 

0.26 

• 

CNI 

0.12 


There was general agreement among all companies visited that 
there was no problem in meeting the hydrocarbon and carbon-monoxide 
limits with existing gas turbines, and that a level near 2.0 g/mi NO 

X 

could be reached with fixed-geometry combustors. The use of variable- 
geometry combustors to reach the lower NO limits would entail addi¬ 
tional manufacturing costs of at least $40 (Ford projection) because 
of the more complex burner and control system required. 

Ford, Chrysler, and GM were in agreement that gas-turbine 
engines, which would be available for production in the 1980's, would 
have fuel consumptions in the federal driving cycle lower than the 

average of spark-ignition engines controlled to meet 1974 emissions. 

129 

Ford, in particular, forecast sharply lower consumption. It felt 

that the miles per gallon of production vehicles would be 407 o higher 




183 


than that of 1974 spark-ignition-engine cars in 1983 and 130%, higher 
in 1990 (3,000°F TIT). Poor idle fuel consumption has been the 
chief cause of poor mileage in urban driving, and the higher TIT 
levels projected tend to reduce this deficiency. Calculations 
verify that with Ford's projected component performance (turbine 
efficiency = 91%, regenerator effectiveness = 92%, compressor 
efficiency = 85%, leakage = 2%%, and pressure drop = 10%), and with a 
turbine inlet temperature (TIT) of 2,500°F, that the projected fuel 
economy is reasonable to obtain. The component efficiencies listed 
above are on the optimistic side, which implies that very careful 
development will be required to achieve the above-mentioned fuel 
economy. Ceramic turbines, nozzle rings, combustors, and heat 
recovery units are required to achieve the full advantage in fuel 
economy. 

The most significant change in the outlook for the gas turbine 

122 129-131 

results from the general agreement among U.S. manufacturers 5 
that it can be a technically superior engine to the spark-ignition 
engine at least down to 100 hp, and probably to 75 hp. If Ford's 
predictions are confirmed, a 75-hp gas-turbine engine would have a 
lower fuel consumption than a 40-hp spark-ignition engine, thus 
tending to rule out the use of minicars as a necessity to reach high 
mileage. 

Moreover, gas turbines of any size are intrinsically long-life 
engines, as demonstrated in the aviation industry. Their use will 
give an incentive to the design of long-life chassis and to the 
consequent reduction in materials use. In contrast, spark-ignition, 
internal-combustion engines as used in automobiles are comparatively 
short-life engines, with life decreasing as size decreases. 

The configuration of the gas turbine for automotive use, which 
has been regarded as standard, has a centrifugal compressor, one or 
two rotary regenerators, a combustor, and an axial turbine as the 


184 


so-called 'gasifier 1 section, and a separate-shaft axial turbine with 

. , i , , f . , . . 130-136 

variable-angle nozzles forming the power section. 


This basic 


configuration was used by GM in their demonstration of low emissions. 

137 

In the last two years, there has been increased study of 

, £ , . 122,129 , 

and acceptance of the single-shaft gas turbine concept which 

achieves considerable simplification by dispensing with the power turbine. 

However, some form of infinitely variable transmission is required to 

take power from the shaft driving the compressor, whose speed must be 

maintained at above 507 o design speed. Various types of transmission are 

being studied, but nonehas yet been demonstrated with a single-shaft gas 

turbine. 

Present U.S. vehicle turbines use peak-cycle temperatures in 
the range of 1,850 -1,925 F. It is generally accepted 

that 2,200°F is achievable with existing technology. It is anticipated 
that temperatures will be increased over the next six years to 
2,500°F, 9 anc j possibly to 3,000°F.^^ The most likely means for 
withstanding these temperatures in the combustor, nozzle and turbine 
is the use of silicon carbide or silcon nitride. Ford, with in-house 
and ARPA funding, is developing a dual-density turbine wheel with a 
hot-pressed hub and molded blades, both of SiN^. Indicative of the 
increasing effort on ceramics for gas turbines are References 138-142, 
showing the high potential of silicon carbide and silicon nitride. 
Alternative ways of reaching high temperatures are to use gas or liquid 
cooling and to employ coated refractory (molybdenum) alloys. 

Design of gas turbine for the high inlet temperatures required 
to achieve competitiveness with gasoline engines is a new science 
that is some years away from maturity. Casting and firing ceramics, 
use of refractory metals, and strong cooling of blades and nozzles 
are all expensive at this time. They are all in the early development 


185 


stages for automobile engines. There is no established certainty that 

any of these methods of utilizing high turbine inlet temperatures can 

be developed for a low-cost engine. Also, there is some feeling among 

development engineers that the potential performance gains associated 

with higher turbine inlet temperatures will be dissipated by increased 

143 

losses due to the reduced Reynolds number. 

The cost of anti-friction bearings can be high. Chrysler uses 

130 

plain bearings presently. Gas bearings of the foil type seem 

129 

attractive as a future development. 

Present problems with ceramic heat exchangers have been 

identified as due principally to sodium substitution from road and 
, 129 

sea salt. New ceramic materials will be required. Some potential 

candidates have been found and are being evaluated. 

Studies have been made, and are continuing, on gas-turbine 

costs to the consumer.^^ , ^^’^" r ^ Above 150 hp, it is possible that 

they could be near competitive with spark-ignition engines,but they 

143 

become much less competitive below 100 hp. The cost structure is 

not clear at this time and must be made firm with more experience in 
small gas-turbine manufacturing. 

The estimates made in the April 1973 report (Reference 116) still 
seem valid--that limited production of gas turbines could start in 1982 
and mass production in 1984. These estimates assume an intense and 
continuing effort. 

The costs of changing the automobile industry's 46 engine lines 

to gas-turbine production (ceramic components) have been estimated by 

129 

Ford to be $250 million each, or a total of $11.5 billion. This 

cost would be additional to the normal costs of production changes. 
Ford's estimates show the possibility of the investment being equalled 
by the value of the fuel saved (at about 65 cents per gallon) within 
five years. 


186 


All foreign manufacturers appear to be well behind U.S. companies 
in automobile gas-turbine development. Their predictions are also much 
more conservative, reflecting U.S. views of five or ten years ago. 

12.3 Rankine-Cycle Engines 

Rankine engines for automobiles are basically of four types: 
steam with positive-displacement prime mover, steam with turbine 
prime mover, organic fluid with positive-displacement prime mover, 
and organic fluid with turbine prime mover. Another broad category 
of Rankine-cycle engines--those using liquid metals--is not being 
considered for automobiles. 

Steam has been used the longest of any of the available working 
fluids, and reciprocating prime movers have been used the longest with 
steam. Other fluids were investigated as the need developed for high 
power density in the prime mover and for efficient low-temperature 
cycles. Rankine cycles are subject to optimization for peak efficiency, 
or reduced size, or reduced cost as a function of fluid and design 

conditions. Conclusions based on Rankine-cycle optimization and hard- 

116,127,145-164 , J , 

ware investigations are that steam will lead to the 

lightest and most efficient simple Rankine engine for automobiles. The 

efficiency of simple steam cycles is generally limited to about 25% 

at the best operating conditions; organic Rankine cycles are generally 

limited to about 207, at the best operating conditions. Thus, organic 

fluid power plants have boilers a minimum of one quarter larger than 

equivalent steam plants, and the condensers need to be at least one third 

bigger. Many organic fluids also have thermodynamic properties that 

require recuperators to be built into the power plant. 



187 


The last two years have seen significant development strides 

in steam automobile engines. Efficiency has been pushed to near 

the probable, limit for simple steam engines in at least two development 

programs , and in one of these development programs, the weight 

and volume have been brought down, to be near competitive with the 

147 

small engine that it replaced. 

Also, the latter engine, described in Table 12.1 (Carter) has 
demonstrated in actual tests that the 1978 emissions goals have been 
met with competitive mileage in an auto having an overall weight of 
2,750 lbs: 


14.9 

- 

MPG 


HC 

- 

0.399 g/mi 

CO 

- 

1.08 

g/mi 

NO 

X 

- 

0.33 

g/mi 

WT 

_ 

415 

lbs 


This steam engine has been fitted into a small car (a VW station 
wagon). Figure 12.1 shows three photographs of the car and 
components. The engine filled the compartment of the air-cooled SI 
engine it replaced. In addition, a 35" x 16" x 2%" ram air radiator 
mounted at the front of the car is satisfactory to 60 mph. A small 
additional radiator with a fan is mounted in the engine compartment. 
Fixed cutoff is used. A transmission and variable boiler pressure 
is used to vary power and torque to the wheels. The boiler 
pressure is allowed to change in response to power demands. Boiler 
pressure, water rate, steam temperature, and F/A ratio are all 
controlled. These innovations lead to simplified controls. The 
steam is held closely (+15°F) to design temperature at all times to 
allow the efficiency to be as high as practical over the operating 
range. The prime mover is a very light piston engine using a unique 


188 


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FIGURE 12.1 



Rear View of VW with Carter Steam Engine Mounted. The Grill 
Covers the Boiler Stack and the Rear Condenser. 



The Prime Mover Showing the 4 Cylinder 















190 


Continuation of FIGURE 12.1 





The Boiler-Burner Assembly. 


Source: Reference 147 















191 


valving system and uniflow design that lead to high prime-mover 
efficiency. Extremely good lubrication is achieved which promises 
to lead to very long prime-mover life. A centrifuge is used to 
separate oil from the feedwater so that oil will not affect the 
design or operation of the boiler and condensers. The flow chart 
for this engine is indicated on Figure 12.2. 

The demonstrated starting time to high-speed idle is less than 
15 seconds. Time to reach driving power is 27 seconds. The emissions 
of this engine are not the best that could be expected, but it is not 
because of the engine design. Rather, the application of principles 
of combustion design developed in other companies 5 could easily 
reduce the emissions further without affecting the engine in any 
significant manner. 

Good strides were made in the development of another steam 

148 

engine designed for a larger car. This engine is presently 
mounted on a dynamometer being readied for simulated driving. 
Steady-state measurements indicate that the mileage will be near 
competitive to 1974 vehicles. Very good emission results are also 
indicated. Table 12.1 describes the SES engine. 

A third steam engine presently starting driving tests in a 

small vehicle (2,500 lb) demonstrates very good emissions in its 

146 

preliminary tests. Also, mileage appears to be approaching that 
for emission-controlled, gasoline-engine-powered automobiles of the 
same weight. Table 12.1 describes the SPS engine and the 
characteristics of an advanced version as anticipated by SPS. 

The Aerojet steam turbine engine built for the "California Clean 
Car" is also described on Table 12.1. It is not as far along as the 
others. The Thermo-Electron organic fluid engine is also described 
on Table 12.1. This engine development was being supported by EPA 
and Ford. Ford has declined to fund this program further. 


192 



FIGURE 12.2 Flow Chart. 


Source: Reference 147 











































































193 


Cost is the major unknown factor for Rankine engines. With the 
continued development of manufacturing techniques for boilers, with 
the use of the simple controls already demonstrated on one of the 


existing engines 


147 


with the use of burners having emissions as low 
126,127,144,148,149 


as has been demonstrated already,""" 5 and t h e use G f 

147 

the lightweight, simple, well-lubricated prime mover discussed herein, 

the cost of the engine probably can be brought down to within 507> to 

1007 o of the equivalent pre-control spark-ignition gasoline engine. 

The prime movers and the accessory drives could, conceivably, be less 

costly than the equivalent SI engine. The control system demonstrated 

147 

on the small steam engine in the VW station wagon is the simplest 
of the Rankine-engine control systems being developed on EPA or State 
of California contracts. 


12.4 Stirling Engines 

Basic findings on the Stirling engine as reported in Reference 116 


are still valid with some minor modifications. Developments in Stirling 

. , 163-168 

engines for automobiles over the last two years 


have centered 


around installing two experimental versions in marketable auto frames. 

A 175 hp engine has been operating on a dynamometer in the Netherlands 

165 

and will soon be mounted in a Ford Torino, and a 100 hp engine has 

166 

powered a Ford Pinto to as high as 65 mph on a flat track. A CVS 

test simulation indicates emissions of an intermediate-size auto will be: 


165,166 


HC 

CO 

grams per mile 

N0 X 

MPG 

0.20 

1.20 

0.14 

14.7 


These engines are described in Table 12.2. 





















































































193a 


TABLE 12.2 


HP 

Emissions 

Type 

Mechanism 
Fluid 
Rod Seal 
Control 

Peak Temperature 

Engine Efficiency (Peak) 
(see plot below) 

Radiator Area 

Market Goal for 
C pecific Engire 


Stirling Engine Description 

Philips 

170 

0.20 HC, 1.20 CO, 0.14 NO 

x 

double acting 
swash plate 
hydrogen 
roll sock 

variable mean pressure 
1400°F 

32% 

automobile 


United Stirling 

100 

double acting 
V-4, crankshaft 
hydrogen 

rod clearance control 
variable pressure amplitude 
1400°F 

25% 

3 ft 2 (3" thick) 
replaces small diesel 


Fuel Economy Map - 4-215 Engine 



125 (kw) 
100 (kw) 
75 (kw) 

50 (kw) 

25 (kw) 
10 (kw) 


ENGINE SPEED (rpm) 














194 


What is now apparent for Stirling engines is that by tailoring 

the efficiency slightly, an engine of appropriate power for an 

existing automobile can be of low enough weight and size, and have 

sufficient response time to be indistinguishable from gasoline-powered 
165 166 

automobiles. ’ They are very quiet, the fan and blower noise being 

the largest contributor to noise; they are very smooth in any workable 

configuration; they can be made to be very low-emissions engines, 

they will have low fuel consumption, somewhere close to a nonemission- 

165 

controlled diesel engine; and they can have exceptional life. On 

the other hand, the radiator will be harder to fit into a standard 

automobile.’^6 Cost and production problems have not been resolved 

so that the present cost projections show competitive values to diesel, 

but not to spark-ignition, engines. 

Predicted emissions were reported in Reference 116 and still 

apply. No direct measurements with Stirling engine-equipped cars have 

been made. However, the emissions should be very low.’*’^ ^2 

It is also apparent that the present developers feel that they 

165—167 

are at the threshold of the next steps in dramatic improvement. 5 

171,173,174 „ . , 166 . 

These involve incorporating cheaper materials, improving 

166 167 

the power control system to be cheaper and more efficient, ’ and 

more completely integrating the engine into the power train to better 

165 

meet the driver's demands. They are now better able to cope with 

optimizing for different applications such as automobile duty, medium 
duty, and heavy duty. Much remains to be done, and at present rates 
of spending (about 230-men average load over the world), it will still 
be three to four years before an acceptable automobile engine will be 
in existence. 

The Stirling engine must still be regarded as an experimental 
engine for automobiles. While the basic engine is understood, there 
are a large number of design compromises needed (and unsettled at 


195 


this time) before the proper development direction can be chosen for 
particular applications. For instance, it is known that fully 
metallic engines can be of high efficiency and be quite small and 
light, but they are expensive. On the other hand, ceramic parts 
should fit very well into several places of the Stirling engines. 

This should ultimately lead to inexpensive engines. However, it is 
not clear which parts will be cost effective to switch to ceramics 
in mass production, there are no suitable ceramics in mass production 
for use in such applications, design compromise to use ceramics in 
such engines is just starting to be a known art, and efficiency 
Versus size of Stirling engines as affected by ceramics is not yet 
assimilated into the technology. The ceramic work being done on 
behalf of gas turbines can also be applied to Stirling engines. 

a. Stirling engine characteristics -- The objectives for design 
of a workable Stirling engine beyond that required for any positive 
displacement engine, primarily are as follows: 

. prevent fluid leakage from inside the loop to the outside 
past the power shaft or rod to keep the engine operable; 

. keep all volumes outside the swept volumes as small as 
possible for highest specific power density; 

. minimize pressure losses as the fluid moves back and forth 
through the heater, regenerator, and cooler for high 
efficiency and greatest power control range; 

. handle as much fluid as possible for best specific 
power density; 

. operate at as high a peak temperature as possible for 
high efficiency; 

prevent loss of heat from the hot side to the cold side for 
high efficiency. 



196 


These translate into a requirement to use pressurized hydrogen or 
helium as the working fluid. The classic problems of Stirling 
engines that also arise from the above list of requirements are: 

(1) Heater head: 

. Requirements are small volume, large area, low fluid 
pressure losses, high-temperature materials. Usually 
forces the use of or He under high pressure as 
the working fluid; 

. Makes thermal stress a severe problem; 

. Makes for high-cost materials and construction 

technique. 

(2) External seal and working fluid diffusion losses: 

. Requires either very low loss so one charge lasts a 
tolerable time without power loss, or requires that 
the engine be rechargeable. 

A third classic problem arises when consideration is given 

to changing power level: 

(3) Power control: 

. Requires very rapid method of changing fluid quantity 
and/or method of changing pressure amplitude variation 
with a fixed-fluid quantity, to be workable at any 
engine speed. 

All of these problems contribute to the potential cost. 

Practically all of the development work going on at this 
time, beyond making the engines operable in automobiles, is toward 
technologically suitable solutions of the three major technical 
problems. Designs which appear suitable for lowered cost are to be 


197 


developed later from these solutions, so that lower engine costs 
follow by normal cost reducing methods. One developer is aiming for 
a car installation that will have run a total of 50,000 miles by 
December 1975. 

It is worth noting that the safety of automobiles has 
been checked when the hydrogen-working fluid inventory has been lost 


into the engine compartment. No significant hazard appears to exist. 

b. Future possibilities -- It is apparent that much ingenuity 
has yet to be expended on heater-head design. This thinking is being 
tempered by the great desire to incorporate ceramics into many parts 
of the design for very high-performance engines. However, the only 
ceramic part in any existing automobile-type engines actually 
running is the rotary air preheater. Time limitations imposed by 
the automobile company contracting for Stirling engines (Ford) 
have precluded including extensive development work in ceramics at 
this time. 

The control situation is till pregnant with concepts yet 
to be tried. The ones being used presently are the variable-mean- 
pressure type, and the variable-pressure-amplitude type. A 
simplified variable-amplitude type makes use of fewer valves, with a 
goal of simplifying to one set of valves for control of all chambers. 
Philips is reconsidering the variable-pressure control to see if it 
can be improved. MAN is working on a proprietary system that would 
bypass the major drawbacks of the variable-amplitude and variable- 
pressure systems. 

Sealing appears to be a tractable problem, more in that i^t _ 
be designed around, as well as partially solved by, direct attack. 
United Stirling uses a sliding seal with provision for onboard 
hydrogen makeup. Yearly leakage of a 100 hp engine would be about 
4 lb of hydrogen based on their existing data (about 100 refills 
per year). Philips uses the roll-sock seal for stopping leakage 


175 



198 


at the seal, and only a yearly check of hydrogen inventory is needed. 

The prime movers are all presently piston-type, positive- 
displacement devices. At least one patent has been issued to an 
auto company for use of rotary positive-displacement devices. Assuming 
the mechanical seal problem associated with such configurations can 
be solved, development could lead to an engine of small overall 
prime mover size simply because the drive mechanism would now be 
better incorporated into the package design. The largest part of 
the prime mover sections of existing Stirling engines is the drive 
mechanism, be it rhombic drive, connecting rods and drive shaft, 
or swash plate. A V-4 engine is fitted into the Pinto, and a swash 
plate engine is being fitted into the Torino (Philips 4-215 engine). 

One additional concept worth noting is that one developer 
thinks highly of a method that incorporates a variable swash plate ^ 

into the drive design that would essentially eliminate the transmission. 

The Stirling engine leads itself well to operation with stored 
165 

head. The engine can be combined with a thermal storage system 
(thermal battery) to operate either with sensible heat, heat of 
fusion, or both, depending on the heat storage material. One research 
group believes that small cars using Stirling^ngines with thermal 
storage units are practical for urban driving. Projected heat 
storage capacity using fluoride or eutectics of fluorides at 
550-860°C range from 0.33 to 0.47 kwhr per kg or 0.72 to 0.93 kwhr/dm. 
About 357> of this is deliverable as mechanical energy. The delivered 
energy density would be 50 to 70 whr/lb compared to about 10 to 12 
whr/lb for the best existing lead-acid traction batteries. This 
system would be a competitor to the small battery-powered urban car. 

The BTU energy balance favors the battery system, but the thermal 
system can be lighter. Costs of the thermal system are not yet 
worked out. 


199 


12.5 Reciprocating Brayton-Cycle Engines 

These engines use reciprocating parts to accomplish compression 
and expansion. The cycle is basically the same as for gas turbines, 
and all of the thermodynamic options open to gas turbines are open 
to reciprocating Brayton engines: 

1) Air working fluid, with heat recovery, internal firing 

2) Air working fluid, with heat recovery, external firing 

3) Air working fluid, no heat recovery, internal firing 

4) Air working fluid, with heat recovery, external firing 

5) or He working fluid, with heat recovery, external firing. 

Only the last one has been studied experimentally in the last few 

years; types 3 and 4 have been in the patent literature for decades. 

Thermodynamic performance demonstrated to date on Type 5 is quite 

poor (about 12%), but an efficiency on the order of 277 o -307 o should 

be attainable using the same materials, etc., that would be used in 

176,177 

the equivalent Stirling engine. The Brayton engine has the 

advantage that pressure losses due to small heat exchangers can be 
avoided and that power density is not sensitive to external volumes. 
But, it has the disadvantage that one set of hot valves is needed. 
Otherwise, the Stirling engine and externally fired Brayton engine 
with U or He working fluid have many of the same characteristics. 

The Brayton engine has some design flexibility advantage over the 
Stirling engine in that more freedom on pressure ratios exists. This 
may be an academic advantage, however, since present Stirling volume 
ratios appear near optimum. Because the Brayton engine relies on 
isentropic processes for compression and expansion instead of iso¬ 
thermal heat transfer processes (as in Stirling), and because the 
Brayton engine uses a recuperator rather than a regenerator (as in 
the Stirling) for cycle heat recovery, the Brayton engine thermodynamic 
efficiency runs somewhat lower than for a Stirling engine operating 



200 


between the same temperatures. A recuperator transfers heat between 
two fluid streams with an effectiveness of 85% or less except where 
large volumes can be tolerated. A regenerator collects heat from a 
hot fluid, stores it, and later transfers it to a colder fluid with 
effectiveness that can range up to 98%. The meaning of these trade¬ 
offs is that the Stirling engine should be able to attain higher 
efficiency at the same or less cost, but that the design problems are 
more difficult than for the reciprocating Brayton cycle. 

The use of air in reciprocating Brayton engines is possible 
from a practical point of view because the heat exchangers can be 
designed for air without compromising the engine power density and 
efficiency. The operating conditions of the engine are limited, 
however, by the action of hot air on the materials of construction. 
Whether internally or externally fired the same limitations apply. 
Internal firing has the advantage of reducing heater size and cost, 
but could lead to poor emissions if the performance is to be 
satisfactory. External firing has the same limitations as for the 
or He engines. 

If the problems associated with achieving a suitable Stirling 
engine design of the conventional type prove insurmountable from a 
cost point of view, then the reciprocating, valved, Brayton engines 
will be worthy of further consideration. 

12.6 Flywheel Systems 

Flywheels of new designs offer the possibility of very high 

178,179 

energy storage density. A flywheel with sufficient specific 

storage capacity to drive a car in a conventional way requires a 
sophisticated design, a vacuum chamber to run in, and a seal and 
vacuum pump for maintaining the vacuum. The drive requires an 
alternator with a variable-speed, variable-frequency type converter 
or variable-speed, constant-frequency converter with additional 



201 


control for electrical drive or an infinitely variable transmission. 

Thusafor the electrical drive, the drive system alone will cost 

one and one-half to two times the engine and transmission it replaces. 

174 

This is the same as for battery-drive vehicles. In addition, there 
is the cost of the flywheel assembly. Unlike battery drives, there 
is little probability that the flywheel could be an easily replaceable 
unit for quick change at a service station. Thus, the flywheel has 
to be considered part of the automobile's first cost to the customer 
rather than an operating cost as with gasoline or easily replaceable 
batteries. Flywheels and their vacuum chambers suitable for 200-250 
mile range will probably cost on the order of an uncontrolled engine, 

sized for similar service, based on estimates available in preliminary 

178 

studies. Special transmissions, vacuum devices, chargers and 
controls, or electrical drives are additional. Also, the demonstration 
of such a system in an automobile, irrespective of cost, is several 
years away. 

Use of an infinitely variable transmission would bring the 
power plant cost down to that of the flywheel assembly, the transmission, 
a gearbox, and a charging motor. The total cost may conceivably be 
brought down to one and one-half to two times that of uncontrolled 
spark-ignition engines if the flywheel assembly can really be made to 
cost the same as an uncontrolled spark-ignition engine. Demonstration 
of this cost probability and demonstration of the flywheel system 
in a vehicle would be required before it could be considered seriously 
as an automobile drive. The safety aspects of flywheel operation 
will also have to be demonstrated in a vehicle, although the frangible 
flywheel using glass fibers has been shown to disintegrate effectively 
without problem when malfunctions occurred. The emissions would take 
on the nature of the central powerplant, similar to battery systems. 


202 


12.7 Electrically Driven Vehicles 


a. Introduction -- The assessment of the performance of present 

and anticipated electrically driven vehicles as presented in Reference 116 

requires additions and corrections in the light of new developments. 

180“186 

Recent vehicle systems studies, battery and vehicle test pro- 

186-189 J J . u U1 190-194 

grams and advancements m battery technology allow a more 

concrete appraisal of future vehicle capabilities. The gasoline fuel 
shortage experienced during the past year, as well as the rapidly rising 
cost of crude oil, have provided a powerful spur for seeking alternative 
power sources for transportation. Electric vehicles, at least on super¬ 
ficial examination, seem to offer potentially significant fuel savings. 
(183,188,195,196) 


It is well understood, of course, that the use of electrical 
drives in vehicles entirely removes the polluting source from the vehicle 
and transfers it to the central power plant. The cleaning up of emis¬ 
sions from power plants need not be considered here; this problem is 
already receiving intensive attention. The additional power demand by 
electric vehicles seems not serious considering the unavoidable low rate 
at which such vehicles could be added to the present transportation 

scheme. For instance, if all driving in the USA were by electric cars 

12 

(approximately 10 miles per year) requiring about 0.4 kwhr/mi, the 
nighttime average electrical generating capacity required for charging 
would be about 150,000 megawatts. This is not much greater than the 
present nighttime excess generating capacity in the United States. 

Gradual introduction of electrical vehicles should result in demands 
less than the excess capacity. 


b. Batteries -- Results of recent test programs and of develop¬ 
mental efforts lead to the following assessment of present and future 
capabilities of batteries: 





203 


(1) The lead-acid battery is the only currently available 
electric sotrage system for automotive traction with a reasonable cycle 
life and cost per unit energy stored. Its key limitation, energy storage 
density, can be improved sufficient (from 10 to 12 whr/lb to about 13 

to 15 whr/lb) but this is not to permit application beyond marginal- 
performance urban vehicles, delivery vans and busses. Even if the 

cycle life were to be extended to 1,000 deep cycles, the amortization 

of the battery over its lifetime will lead to a cost of the battery 

i . 0 c j 180-182,184 

alone amounting to 3-5 cents per kwh delivered. 

(2) Other battery systems with "intermediate" performance 
will very likely become available within the next five years; 

see Table 12.3. Although these promise to provide two-to-threefold 
improvement in energy density, relative to the lead-acid battery, it 
is unlikely that their cycle life can be sufficiently improved to 
provide economically attractive energy storage cost. However, because 
the future Zn-NiOOH system may have good power capability, its applica¬ 
tion in electric vehicles and perhaps in gasoline-electric or battery- 
battery electric hybrids deserves consideration. 

(3) Recent advancements in the technology of the solid 

electrolyte (beta-alumina), as well as in other critical areas affecting 

the feasibility of alkali metal sulfur systems, increase confidence 

in the eventual technological feasibility of high-energy, high-power 

18? 192 195 

density battery systems. 5 ’ Prototype producing and testing 

programs should provide definitive answers in the next three to five 
years as to whether the alkali-metal-sulfur batteries can provide an 
economically viable solution to the energy storage needs of electric 
vehicles. Indications at present (Table 12.3) are that battery 
amortization costs may achieve a level below 1/cent/mile. Current 
work on the feasibility of battery schemes employing alkali-metal 


204 


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negative electrodes at lower temperatures (in the range of 200°C) 
shows good initial promise. Significant advantages in cell 
construction technology and cost may be derived from operation at 
this lower temperature level. Production of significant numbers of 
electric vehicles based on alkali metal batteries cannot be expected 
before 1985 at best. 


c. Electric drive train -- There are a number of viable 
alternatives for motor and switch-gear systems suitable for use in 
electric vehicles. Systems studies and experimental test programs 
indicate that electric systems which have favorable torque and 
speed-control characteristics combined with high efficiency will have 

initial costs (excluding the battery) comparable to or higher than the 

,. , „ 182,183,185 

present-day drive train of gasoline-powered automobiles. 

Weight of the drive train depends greatly on the system, although 

the order of magnitude appears to be about \\ to 2 kg/hp. The VW 

van being worked on at DAUG and VW suffers a weight penalty of about 

100 to 200 lbs for an electric vehicle without batteries compared to 

a gasoline-engine-powered van. Motor and switch gear possessing 

optimal characteristics for electrics are not yet fully developed. 

The drive train aspect of electric vehicles, however, does not appear 

to present the limiting factor in the eventual realization of 

efficiency and economically attractive electrical vehicles. 


d. Hybrids -- Recent tests by EPA on a gasoline-engine-battery- 

198 

hybrid vehicle (Petro Electric) demonstrated with a 4,000 lb vehicle 
the following emissions and fuel economy over the Federal Driving 
Cycle: 

HC CO NO MPG (avg) MPG (engine off at idle) 

x 

(grams per mile) 

0.45 2.08 0.90-1.14 10.4 


12.4 




206 


A Wankel engine and lead-acid batteries were used. The driveability 
of this vehicle was acceptable. Further improvements in meeting emis¬ 
sions standards and in gas economy can be expected by using a conventional 

small gasoline engine rather than the Wankel employed in this test vehicle. 

185 187 

Other test programs involving hybrids 5 have not produced as yet suf¬ 
ficient data on emissions characteristics and on energy efficiency to 
make meaningful conclusions possible. Because hybrid drive systems are 
more complex than either of the derivative systems, the initial cost of 
the vehicle promises to be high. However, the anticipated longer cycle 
life of advanced battery systems may provide a basis for favorable 
vehicle cost per mile. 

/v 

Tests conducted at EPA in October-November of 1974 with the 
Petro-Electric vehicle yielded the following results: 

HC 0.38 g/mi 
CO 2.41 g/mi 
N0 X 0.76 g/mi 
MPG 9 urban 

16 highway 

These results were obtained at 4,000 lb inertia weight and with a high 
rear-end ratio. The mileage is for the battery recharged to its 
starting level. A rotary engine is used in conjunction with the elec¬ 
tric system. Using an EPA determination factor for a rear-end ratio one 

half that used in the test, and the improved economy of a piston engine 

£ 

versus a rotary engine, the predicted urban mileage would be 1.35 x 2’ x 
measured value = 17.9 mpg. Past EPA tests on the Petro-Electric vehicle 
have indicated highway mileage nearly double the urban mileage. 

The electric system includes a set of starter, light, and ignition 
(SLI) batteries having 90 amp hours of storage. Discharge is only by 
2 amp hours before recharging starts and does not normally exceed 6 amp 
hours during operation. Also included is an electric motor rated at 
10 hp continuous, or 20 hp for one minute, or 40 hp for acceleration. 


* Telephone call from H. Wouk, President, Petro-Electric Motors, Ltd. 
to J. Bjerklie, December 12, 1974. 



207 


Costs have been resolved except for the batteries and the motor in 
large production. Including these items, the purchase cost of the Petro- 
Electric vehicle would be between 10%-20% higher than the equivalent 
gasoline-engine-powered vehicle for the same emissions and performance. 
(Note: This information was approved and added to the consultant report 

December 13, 1974.) 


181,195, 


(e) Power demand -- Most recent estimates on power demand 

196 199 

’ to be created by electric vehicles tend to confirm earlier esti¬ 
mates according to which the availability of centrally generated electri¬ 
cal power and of distribution network is not likely to present a constraint 
on the introduction of even a moderately large population (i.e., addition 
of 1-2 million vehicles/year) of such vehicles. Because of the load 
leveling potential of electric vehicles (i.e., charging during off-peak 

periods), economical benefits may be derived from such a power demand 

196 

resulting in lowering the average cost of power. In the planning of 

central load leveling facilities, it would be of distinct advantage to be 
able to rely on competent estimates regarding the expected penetration of 
electric vehicles in the transportation system. 


(f) Energy economy -- The energy requirement of an electrically 

driven vehicle compared to that of a gasoline-driven car has been 

£ u J 180-184,188,195,196,199 „ 

estimated by a variety of methods. Because of 

the paucity of road-test data on electrics, a fully reliable comparison 

is still not available. One of the key difficulties in making a valid 

comparison between even the smallest gasoline-driven automobile and an 

electric vehicle available for road tests is that at present the only 

battery system (i.e., the lead acid) at all suitable for vehicular 

application provides extremely limited power and range. Once we put 

together on paper an electric car with performance similar to at least 

the smallest cars on the road today (Honda, Pinto, Vega, VW, etc.), 




208 


we must anticipate performance of batteries which are not yet 
available. 

Keeping the foregoing remarks in mind, recent system-performance 
studies provide the following estimates: 

The energy requirements per mile of lead-acid-driven electrics 

using current technology for the frame and driving train are comparable 

182 184 

to the subcompacts on the road today ’ (0.25 to 0.5 kwhr/mile). 

This disappointing performance results from the very high weight of the 
battery required for even a marginal vehicle range and marginal accelera- 
tion/hill-climbing capability. 

The energy requirements per mile for cars powered by "intermediate"- 
type batteries (e.g., NiOOH, Ni-H 9 ) can be expected to be comparable to 
those of current subcompacts. The higher energy density and power density 
of these intermediate battery types will considerably reduce vehicle weight. 

The energy requirement of electrics using alkali metal-sulfur 
batteries, with energy and power densities in the range of 100 kwh/lb and 
100 wh/lb, respectively, should be somewhat lower than present-day, 
gasoline-driven vehicles (compacts) with comparable performance. 

It is worthwhile to compare the amount of raw fuel required 
per mile to drive electric and heat-engine-powered vehicles. From 
the results indicated above, it can be assumed that electric cars com¬ 
petitive to subcompact gasoline cars will require an average of about 
0.35 kwhr/mile. On the other hand, a family-size car averaging 15 mi/ 
gal requires about 0.45 kwhr/mile. This would correspond to an intermediate- 
size car powered by a Stirling engine. The conversion of raw fuel to 
drive-shaft power would be approximately as follows: 


209 


Electric Car 


Fuel processing efficiency = .9 

Power plant efficiency = .32 

Trnasmission line efficiency = .91 

Battery charge/discharge efficiency = .7 

Motor/control efficiency = .8 

Transmission and gear = _ 

Overall efficiency = .146 


Heat Engine 

.9 

.19 


.9 


.154 


Adjusting for the difference in kwhr mile required by the two modes 
of transport, the ratio of electric vehicle to heat engine vehicle 
fossil fuel requirements is 0.82. This ratio is low enough to induce 
some interest in electric vehicles at the present time. 

If the transportable fuel of the future requires more 
thermal or electrical processing than indicated above, the energy 
ratio will drop further since the fuel processing efficiency for 
electrical generating plants need not change so long as fossil fuels 
are used. For instance, if hydrogen were to be required for 
automobile fuel in the future, and if it were to be generated 
electrolytically, the ratio will be under 0.6. This should include 
higher interest in electric cars if energy remains a potential major 
national problem. 






210 


g. Summary ; 

(1) There are no alternative engines that can be available 
in mass production for automobiles of standard size 
and performance before the 1980's. 

(2) All of the alternative heat engines can be made to 
meet the 1978 emissions standards, with Stirling 
engines and steam engines able to do so most easily 
and with least controversy on interpretation. 

(3) Present gas turbines show poor fuel economy in urban 
driving, but could be made to show good characteristics 
for touring-type driving. 

(4) High-temperature gas turbines with ceramic components 
for high-temperature portions of the engine should be 
technically competitive with spark-ignition engines 
over 50 hp and should demonstrate excellent fuel 
economy over a Federal Driving cycle. Their economic 
competitiveness is not now clear. 

(5) Stirling engines should ultimately be technically 
competitive with spark-ignition engines over the 
power spectrum used by conventional automobiles. 

It is a necessary, but not sufficient, condition to 
achieve a control system and heater head that can be 
made at a considerably lower cost than at present 
to be economically competitive. 

(6) Steam engines have been shown to be technically suitable 
as an exhaust-clean engine for powering lightweight 


cars. 



211 


(7) None of the alternative heat engines have been shown 
to be suitable in the hands of the public, although 
gas turbines come closet to having done so. 

(8) None of the alternative heat engines have been shown 
conclusively to have a suitable cost structure for use 
in conventional automobiles. 

(9) Light vehicles powered by efficient, externally heated 
engines (such as Stirling), using heat stored in a 
thermal storage system, are being studied for their 
suitability as an urban vehicle. The system has not 
yet been shown to be economically competitive. 

(10) Heat engine-battery hybrids have beem demonstrated 

successfully at the EPA to achieve on the Federal 

Driving Cycle; HC = 0.45 g/mi, CO = 2.08 g/mi and 

NO = 0.9 to 1.14 g/mi, and to negotiate the Federal 
x 

Driving Cycle successfully. 

(11) Flywheel systems have not been shown to be competitive 
with spark-ignition engines costwise, technically, 

or for overall emissions. 

(12) Based on present technology, it is feasible to 
manufacture electrically driven personal vehicles for 
res triced (low range and power) urban use. These 
vehicles, even when equipped with the best, currently 
available, lead-acid storage batteries, will have 
significantly higher initial cost and vehicle cost 
per mile than today's gasoline-driven subcompacts 
with no improvement in overall energy efficiency. 


212 


(13) Active development programs exist for battery-powered 
delivery vans and urbans busses. Their duty cycle 
offers an opportunity that is thought may prove 
economically viable for the introduction of electric 
drives and lead-acid batteries. 

(14) By substantially increasing the cycle life of lead-acid 
batteries, major improvements in energy economy and 
vehicle cost per mile may be achieved by decreasing 

the cost per mile of the battery. Significant 
improvement in range is not likely to be achieved 
with the lead-acid battery. 

(15) Other battery types currently in advanced development 
stage (e.g., Zn-NiOOH, H^-NiOOH) may be expected 
within five years to provide approximately twice as 
high specific energy (range) and significantly improved 
power capability compared to the current best lead-acid 
system. 

(16) The high energy and power density alkali metal-sulfur 
batteries currently under development show good promise 
and should reach advanced testing stage in two to 
three years. 

(17) In view of the strong likelihood for a gradual shift 
toward coal-nuclear-geothermal and, perhaps, solar 
primary energy sources, there are incentives for the 
development of advanced storage batteries for 
electrically driven vehicles. 

(18) A summary of fuel economy data for alternative engines 
is given in Figure 12.3. 


51 Data EPA 
Other As Noted 


213 



<6dw) AIAJ0N0D3 “1303 


FIGURE 12.3 Fuel Economy - Alternative Engines. All Data Are Measured 
Except: Predicted from Dynamometer and Projected from Extrapolation. 






13. ALTERNATIVE FUELS 


13.1 Introduction 

The recent gasoline shortage in the United States has served 
to emphasize the critical dependence of our transportation system on 
a readily available and abundant supply of gasoline. Nearly all 
present-day transportation systems are powered by petroleum-derived 
fuels. Petroleum currently supplies almost 50%, of U.S. energy needs 
with the transportation sector, in turn, consuming about half the 
petroleum. Gasoline for automotive consumption represents 
approximately 75% of this transportation fuel demand, or nearly 20% 
of the total U.S. energy usage. It is not surprising then that 
alternative fuels for automobiles are of great current interest in 
view of government plans to try to reduce the petroleum dependency 
of the United States. 

The subject of alternative fuels interacts in various ways with 
the current Committee on Motor Vehicles study. First, and most 
obvious, the types of fuels available can potentially have a 
significant effect on the performance, efficiency and emissions 
characteristics of the various automotive power sources being 
considered. Thus, an attempt is made here to identify the alternative 
fuels that may become available in the future. 

The type of fuels which will be available will, in turn, depend 
upon the future energy supply spectrum. National policy concerning 
this future energy mix is currently being formulated in terms of 
research and development goals and budgets for nuclear, coal, oil shale 
and other energy sources. The identification of those synthetic fuels 
which are most attractive for automotive applications should serve as 
input to these energy policy decisions. Those alternative fuels 
particularly advantageous for automotive use are identified and 
discussed in the present study. 

Another motivation for considering alternative fuels is the 
interaction between alternative fuels and alternative power plants. 


214 



215 


Many of the alternative power plants are chacterized by continuous- 
combustion systems with relatively little fuel sensitivity, while 
other power plants may require fuels with specific octane or cetane 
ratings. The future availability of fuels of various types may then 
affect decisions regarding production of automotive power plants 
of a given design. The spectrum of available fuels may also affect 
the design of conventional spark-ignited engines, stratified-charge 
engines and diesel engines, and discussion of alternative fuels 
for these engines is included here. 

For the present study, alternative fuels are defined as those 
fuels not derived from the normal petroleum base. Fuels which are 
derived from such sources as coal, oil shale, natural gas or nuclear 
energy resources are considered. Except for direct use of natural 
gas, all of these energy sources require further synthesis or 
conversion to obtain a form suitable for automotive application. 

Hence, the term "synthetic fuel" can also be used to characterize 
fuels from these resources. In the cases where the alternative fuels 
are synthetic gasoline or synthetic distillates, the discussion 
includes information on their potential availability and cost, but does 
not dwell on their application to conventional vehicles. 

The objective of this study is to assess the potential for 
alternative automotive fuels from the standpoint of energy supply 
and cost, vehicle efficiency, performance and emissions. Also, 
where possible, an attempt is made to assess the time frame for 
availability of the various synthetic fuels. 

A summary of synthetic fuel cost and supply data based on 
presently available estimates is given in the next section. Subsequent 
sections contain detailed assessments of the prime non-conventional 
synthetic fuel candidates: hydrogen, methanol and gasoline-methanol 
blends. A discussion of systems employing reformed fuel is also 
included because these systems have potential fuel economy and 
emissions advantages. 


216 


13.2 Candidates, Costs and Time Scales 

Given the energy resource picture for the United States 
and the projections for rates of energy usage, it quickly becomes 
apparent that a heavy reliance on imported petroleum can only be 
avoided by exploitation of non-petroleum, domestic energy resources. 

A typical petroleum demand projection is shown in Figure 13.1, taken 
from Reference 200 and indicates that petroleum demand due to 
transportation alone will outstrip domestic supplies by 1980. 

It is of interest then to consider the possibility of using 
non-petroleum energy resources for synthetic fuel production for 
automotive transportation needs. The available major domestic 
energy resources in this category include coal, oil shale and 
nuclear supplies. Solar and geothermal energy resources may also 
enter the picture, but detailed analyses of their application to 
synthetic fuel production are not readily available. Foreign 
natural gas is the other non-petroleum resource considered here. 

Given these energy resources, fuel candidates, costs and availability 
are analyzed in this section. 

Recent studies performed for the Environmental Protection 

201,202 

Agency by the Institute of Gas Technology (IGT) and Exxon 

203 

Research and Engineering have identified alternative automotive 
fuel candidates and costs based on use of domestic resources. While 
both studies started with a long list of possible fuels, many were 
immediately eliminated for obvious hazard, availability, storability 
or cost problems. The IGT study provided cost data for a number 
of fuels, while the Exxon analysis eliminated all but a few 
candidates for practical reasons before final cost data was completed. 
Cost estimates from these studies in 1973 dollars per million Btu 
at the pump are shown in Tables 13.1a and 13.1b. Current gasoline 
prices (without taxes) are equivalent to about $3.50/10 Btu. 



ANNUAL OIL CONSUMPTION (billion barrels) 


217 



YEAR 

FIGURE 13.1 U.S. Petroleum Supply and Demand (Including 
Natural Gas Liquids). 


Source: 


Reference 200 













218 


TABLE 13.1a 


Cost of Alternative Fuels 




Cost 

at Pump 

Resource Base 

Synthetic Fuel 

$10/ 6 

Btu 

Coal 

Gasoline 

3.00 

(+1.70) 


Distillate 

2.65 

*(+l. 


Methanol 

2.85 

(+2.38) 


Liquid SNG 

3.60 

(+0.94) 


Liquid 

5.65 



^-Hydride 

3.55 


*Co-production (50-50) 

gasoline and distillate 



Oil Shale 

Gasoline 

2.95 

(+1.20) 


Distillate 

2.50 

(+1.20) 

Nuclear Energy 

Electrolytic H 2 




Liquid 

7.60 



^-Hydride 

5.50 



Thermochemical H 2 




Liquid 

6.10 



H 2 ~Hydride 

4.00 



Assumptions : 

Costs are in late 1973 dollars, for investor financing with 
approximately 107> DCF. Capital and operating costs were based on 
published (late 1960's) costs and are probably somewhat optimistic. 

Note: 


IGT has recently completed more detailed cost analyses for 
several of the above fuels. These costs were based on full-size 
plants reflecting maximum economy of scale. Costs included total 
plant investment, 107, overhead, 157, contingency, interest during 
construction, start-up costs and operating costs. Substnatially 
greater production costs were obtained in this analysis. Increases 
are shown in the figures in parenthesis above (Ref. 2a). 


REF 201 








219 


TABLE 13.1b 


Cost of Alternative Fuels 


Cost at Pump 

Resource Base Synthetic Fuel $/10 Btu 

Coal Gasoline 3.33 

Distillate* 2.75 

Methanol 3.85 

Oil Shale Gasoline 2.65 

Distillate* 2.05 


*Produced as coproduct with gasoline 


Assumptions : 

1973 Dollars, 10% DCF Return. 


REF 203 







220 


204 

Jaffe et al . have estimated selling prices for methanol from 
coal for a number of coal sources and gasification processes. Their 
results for methanol from coal, without coproduct, are in the range 
$250-$3.00/10^ Btu for investor financing at 127 0 DCF. Transportation 
charges (about $1.50) would have to be added to these costs to arrive 
at a cost. 

Other estimates for methanol costs are also available. Vulcan- 

Cincinnati Company estimates that methyl fuel (methanol with small 

amounts of high alcohols) could be produced from coal for $1.02/10 Btu. 
206 

Dutkiewicz estimates that methanol produced from natural gas in the 


205 


Middle East could be brought to the United States for $1.05/10 Btu. 

202 203 

Transmission and distribution would add about $1.50 to these costs 

for an estimated total delivered methanol cost of $2.50/10 Btu. 

The time frame for availability of the various synthetic fuels 

is also of interest. The Office of Coal Research (OCR) estimates that 

the data necessary for design of a commerical-size plant for substitute 

207 

natural gas (SNG) production from coal will be available by 1980. 

However, due to increasing demand for natural gas in present markets, 

it is unlikely that SNG from coal would be available for automotive use 

202 

any time before 2000, if then. The state of the art in coal lique¬ 

faction in the United States is not as advanced as coal gasification. 

OCR estimates that the technology for pilot and demonstration plants for 

207 

liquid fuels from coal should become available in the early 1980's.“ 
Allowing time for demonstration plant operation, synthetic liquids 
(gasoline and distillates) from coal will probably not be available in 
substantial quantity before the late 1980's. 

Production of methanol or methane and methanol is another 
possible option for coal gasification plants. This would involve 



221 


first producing synthesis gas (containing large quantities of CO and 
H^) in much the same way as in SNG production. Methanol would then 
be produced from the synthesis gas by commercially available catalytic 
conversion methods. This would have the advantage of producing a 
liquid fuel from coal while requiring only gasification technology 
rather than direct liquefaction technology. An early 1980's time 

frame is then probably appropriate for methanol from coal. Mills 

208 

and Harney have discussed methanol production from coal and 
suggest a production cost in the range of $1.00-S1.20/lO^Btu. Methanol 
is currently produced via steam reforming of natural gas, and it has 

been suggested that natural gas from the Middle East be converted 

206 

to methanol for shipment to the United States. No further 

technological development would be required here. 

Production of gasoline and distillates from oil shale is also 
an attractive low-cost option (Tables 13.1a, 13.1b). Oil shale 
leases have recently been granted and processing plants are being 
designed. The technology for retorting the shale oil to a synthetic 

crude oil is known, and a few plants based on surface mining of shale 

, 209 

will probably be in operation in the early 1980 s. The major 

limitations here are not technology development or processing costs, 
but enviornmental problems and water shortages which may limit 
the scale of operation. 

Cost estimates for either liquid or metal hydride forms of 
hydrogen are relatively high (Tables 13.1a, 13.1b) due to inefficiencies 
in the electrolytic or thermochemical production methods and the 
additional costs for either liquefaction or hydride formation. 
Electrolytic hydrogen production followed by liquefaction is a currently 
available technology, and development of more efficient electrolyzers 
continues. Thermochemical hydrogen production and metal hydride 
storage systems are still in the early stages of development and 
may not be commercially available until the late 1980's. Although 


222 


production of gaseous hydrogen may be relatively cheap (Tables 13.1a, 
13.1b), its low density eliminates it as an automotive fuel. 

Given the above cost and availability estimates, we identify 
the most attractive alternative fuels as follows. Some quantities 
of methanol from either coal gasification or foreign natural gas will 
probably be available as early as 1980. If system studies indicate 
that this fuel should be used in the transportation sector, then use 
of gasoline-methanol blends for automobiles would be an early 
application. Larger-scale production of methanol in the late 1980's 
could result in some use of methanol itself as an automotive fuel. 

The most likely synthetic fuels for the late 1980's and the 1990's 
appear to be synthetic gasoline and distillates from coal or oil 
shale resources. Hydrogen may appear as an automotive fuel, but will 
probably not be widely used before 2000. 

A more detailed discussion of the automotive application of 
several synthetic fuels is included in the following subsections. No 
further discussion of synthetic gasoline or distillates is given since 
these would be essentially the same as presently available fuels. 
Systems which include on-board reformers are also discussed since, 
even though the vehicle may be fueled with conventional fuels, the 
engine will operate with some portion of synthesized fuel. 

13.3 Hydrogen 

During the past few years, hydrogen has received a great deal 
of attention as a potential energy carrier of the future. Its major 
attractions include the absence of carbon in the fuel and the vast 
availability of hydrogen in water. The prime energy sources in 
a hydrogen-energy economy would be nuclear, solar or geothermal, 
and the hydrogen produced from these resources would serve the need 
for an easily transmitted, storable, portable energy carrier. While 
the beginning of any conversion to a hydrogen economy appears to 



223 


be at least 25 years away, many investigations of hydrogen's potential 

as an automotive fuel have already been carried out. The present 

section discusses vehicular storage problems and potential automotive 

engine performance and emissions with hydrogen as a fuel. 

Assuming widespread production and distribution of hydrogen 

as a multi-purpose energy carrier, the major problem accompanying 

its use as a vehicular fuel is the requirement for on-board fuel 

storage. The low volumetric energy density of hydrogen eliminates 

gaseous storage and leaves cryogenic liquid hydrogen or solid metal 

hydride compounds as possible storage modes. Cryogenic hydrogen 

storage systems would occupy four to five times the volume of present 

gasoline tanks, and would require a vacuum-jacketed, specially 

200 213 

insulted tank to minimize boil-off losses. ’ At the present 
time, such cryogenic storage systems would be quite costly, although 
large-scale mass production should reduce costs considerably. All 
of this supposes a method for liquid-hydrogen delivery to individual 
vehicles. Gaseous pipelines to service stations with liquefaction 
equipment or widespread distribution of liquid hydrogen would be 
required. 

Metal hydride storage involves the formation of a solid phase 
metal-hydrogen chemical compound, e.g., Mg H . Although the weight 
fraction of hydrogen in these compounds is usually less than 5%, 
quite high hydrogen storage densities can be achieved by virtue 
of the solid phase. Magnesium or magnesium-nickel hydride systems 

are estimated to weigh 600-700 lb to give an energy storage equivalent 

, 200,210 . . 

to a standard gasoline tank Iron-titanium or magnesium-iron- 

titanium hydrides have operating temperatures and hydrogen evolution 

rates more suitable for vehicular application, but would weigh as 

211 

much as 1,500 lb. The metal hydride decomposition to give the 

hydrogen fuel is an endothermic chemical reaction, and the vehicular 
system would therefore require a provision for cold start-up and 




I 


I 


224 


exhaust-heat recycle to deliver the fuel to the engine. Some 
demonstration hydride storage systems have been built and laboratory 

research programs continue to investigate lighter-weight metal 

212 

hydride compounds. “ Much of this research is being carried out 

at Brookhaven National Laboratory. Widespread use of metal hydride 

storage would, of course, require a metal readily available in large 

quantities. Hydrides can be recharged from a pressurized gaseous 

hydrogen supply so that cryogenic distribution is not required. 

While the vehicular storage of hydrogen requires some research 

and development before widespread practical application is possible, 

the efficient use of hydrogen in the vehicle power plant can be 

accomplished with present-day technology. Hydrogen-air mixtures 

are easily ignited and burn rapidly over a wide range of mixture 

ratios. Alternative engines which employ continuous combustion 

systems (Brayton, Rankine or Stirling engines) are thus readily 

adaptable to hydrogen fuel. The primary combustion zone in these 

systems can be operated much leaner than with hydrocarbon fuels so 

that low nitric oxide emissions are easily attained. 

Application of hydrogen to spark-ignited, reciprocating engines 

requires some engine modifications for proper operation and some gain 

in engine efficiency is possible. We mention here some recent 

experimental results on the performance, emissions and special 

problems of hydrogen-fueled, spark-ignited, reciprocating engines. 

Since hydrogen-air mixtures require only one tenth the ignition 

energy of gasoline-air mixtures, preignition and flashback can be 

problems when operating with hydrogen. Both intake water injection 

and exhaust gas recirculation (EGR) have been used to eliminate 

915 217 

these problems." ’ Both of these techniques also reduce nitric 

oxide emissions and maximum engine power, and water has the 

additional complication of requiring a storage tank which must be 

218 

freeze protected. Direct cylinder induction" ^ and high-pressure, 


225 


21 ^' 219 

direct-cylinder fuel injection - ~ ’ “ y have also been used to eliminate 
flashback and preignition problems. Direct injection has a 
supercharging effect and can increase power output 207 o over a 
carbureted system. 

Engine knock is also a problem with hydrogen-fueled reciprocating 

engines due to the high flame speeds of hydrogen air mixtures. To 

avoid this, it has been found necessary to operate with mixtures much 

leaner than stoichiometric or to employ EGR. Both of these 

techniques result in some loss in maximum engine power. 

A notable advantage of operation with hydrogen is the efficiency 

gain attained through quality regulation of the engine power compared 

with controlling output by throttling. This is possible because 

of the extremely wide flammability limits of hydrogen-air mixtures 

214 219 

and has been shown to give increased engine efficiency. 

Nitric oxide emissions with hydrogen fuel are affected by 

engine variables in much the same way as with gasoline fuel. While 

217 219 

anomalously low emissions have been reported, 5 other 
investigations have shown NO emissions to be similar to operation 


with gasoline. 


214,215,220 


NO control can be achieved by water 


x 


injection or EGR as mentioned previously, and also by very lean 
operation. Extremely low NO emissions can be obtained by restricting 


x 


equivalence ratios to one half or less, although this then requires 

214-220 

a larger engine to achieve the same maximum power. 

In summary, hydrogen is an attractive fuel from an emissions 
and economy viewpoint and can be used to fuel conventional-type 
engines. However, substantial development in vehicular storage 
systems would be required for large-scale use of hydrogen. Such 
large-scale use may be required beyond the year 2000 as fossil fuel 
supplies are depleted. 


I 


226 


13.4 Methanol 


Methyl alcohol (CH^OH), or methanol, has been identified as 

a possible future synthetic fuel and has received considerable 

attention recently. The present subsection discusses automotive use 

of methanol fuel with respect to vehicle performance and emissions. 

Again, the continuous-combustion alternative engines are relatively 

insensitive to fuel type and are easily designed for operation on 

methanol. Thus, the discussion is mainly concerned with methanol- 

fueled, spark-ignited reciprocating engines. 

The use of alcohols as motor fuels is not a new idea. The 

Society of Automotive Engineers held a special meeting on alochol 

221 222 

fuels 10 years ago and Bolt's survey presented at that meeting 
refers to work dating back 50 years. The present discussion is not 
a comprehensive review of alcohol fuels but rather a brief 
evaulation of the principal operational, performance and emissions 
characteristics of methanol-fueled reciprocating engines. Although 

ethyl alcohol (ethanol) does not now appear to be a cost-effective 

202 

alternative fuel, much of the present technical discussion is 
applicable to ethanol as well as methanol. 

A comparison of the physical properties of methanol and 
iso-octane is given in Table 13.2, taken from Reference 223. The 
energy content per cubic food of stoichiometric methanol-air mixture 
is about the same as with gasoline so that the engine power will be 
similar. 

One of the major problems associated with the use of methanol 
is fuel vaporization and distribution characteristics due to methanol's 
relatively high heat of vaporization and large F/A ratios. Experimental 
work with methanol indicates that specially designed carburetors 

and intake manifolds will be required to provide the necessary fuel 

222-225 

evaporation and distribution. The high heat of vaporization 

can, in principle, be advantageous in that it results in cooler 



227 


TABLE 13.2 


Physical Properties of Iso-octane and Methanol 


Property 

Iso-octane 

Methanol 

Chemical formula 

o 

OO 

ta 

i— 1 

OO 

ch 3 oh 

Molecular weight 

114.22 

32.02 

Specific gravity (68°F) 

0.692 

0.792 

Stoichiometric A/F 

15.1 

6.4 

Boiling temperature, F°(K) 

211 (372) 

149 (338) 

Latent Heat of vaporation at 

B.P., Btu/lb (MJ/kg) 

117 (0.490) 

502 (2.101) 

Heating value, Btu/lb (MJ/kg) 

Higher 

20,556 (86.047) 

9770 (40.897) 

Lower 

19,065 (79.806) 

8644 (36.184) 

3 

Energy, Btu/ft of stoichiometric 
mixture (1 atm, 60 F, LHV, 
gaseous fuel) (MJ/m^) 

95.5 (3.559) 

90.0 (3.354) 

Same, liquid fuel 

96.6 (3.600) 

103.0 (3.839) 

Octane No., Research 

100 

106 

Octane No., Motor 

100 

92 


REF 223 





228 


intake manifolds and better volumetric efficiencies as well as less 
compression work in the cylinder. The high heat of vaporization 

also means that methanol-fueled vehicles cannot be started in 
environments below 50°F without the addition of a more volatile fuel 
compound. “ The problem here is vaporization rather than 

distribution, as indicated by tests where manifold injection of 


methanol did not improve cold-starting characteristics. 


224 


It is 


interesting to note that coal-derived methanol may contain small 

225 

amounts of higher alcohols “ which may help alleviate the cold-start 
problem. 

Performance, fuel economy and emissions with methanol have also 

, ,223,225,226,228,229 n . , 

been recently investigated 3 ’ Both single- 

cylinder- engine experiments and tests with properly carbureted and 

manifolded-multicyUnder engines indicate that the lean misfire limit 

for methanol occurs at about 20% leaner mixtures than with gasoline. 

Significant decreases in CO and HC emissions can be obtained by 

operating with these leaner mixtures. Increased emissions of 

aldehydes are generally observed along with some reduction in nitric 

oxide emissions. The principal hydrocarbon emission is methanol, 

which will be removed with water if an exhaust sample dryer is used. 

The methanol response on FID analyzers has been found to be between 

80%> and 100% of saturated hydrocarbon response. Performance and 

fuel economy (on an energy basis) are generally found to be quite 

similar to values obtained with gasoline. Since methanol has about 

half the heating value of gasoline, methanol-fueled vehicles would 

require twice as large fuel storage tanks for the same range as 

gasoline. A 1970 vehicle converted to methanol operation and equipped 

with a special intake manifold and an exhaust-oxidation catalyst has 

met the 1976-77 Federal Emissions Standards without specific NO 

223 x 

control except lean carburetion. This vehicle did experience 

severe cold-start problems until an ether injection system was installed, 


229 


Corrosion of lead, magnesium or aluminum fuel tanks or tank 

coatings has been identified as a severe problem in methanol fuel 
226 

systems. Corrosion of fuel-injector or carburetor parts can also 

be a problem. 

In summary, with respect to reciprocating engines, we find 
that methanol is a suitable automotive fuel for the future providing 
that the cold-start and F/A distribution requirements are included 
in the engine design. This would require major redesign of existing 
engine intake systems. Corrosion-resistant materials would have to 
be used in vehicle fuel tanks and lines including parts of the fuel 
injector or carburetor. Methanol appears to have the capability 
for lower emissions (except for aldehydes) than gasoline, principally 
due to the lower lean misfire limits. Methanol can be burned in 
continuous-combustion-type engines with little or no difficulty as 
long as a suitable start-up system is available. 

13.5 Methanol-Gasoline Blends 

Blends of gasoline with up to 25% methanol have been suggested 
as gasoline "extenders" for present-day vehicles and are currently 

230 

receiving increased attention as a result of recent fuel shortages. 

Like pure methanol, methanol-gasoline blends have long been known as 
potential fuels, particularly for power boost in racing applications 
where fuel injection and very rich mixtures are used. In this 
subsection the fuel mixture and engine performance and emissions 
characteristics of methanol-gasoline blends are briefly reviewed 
and assessed with respect to application to spark-ignited reciprocating 
engines. As with most other alternative fuels, little or no problems 
would be encountered burning these blends in continuous-combustion 
engines. 

Methanol added to gasoline has the effect of increasing the 



230 


octane number of the fuel, although this point has been overemphasized. 
While the research octane number (RON) of modern gasolines is increased 
about four octane numbers (ON) by addition of 10% methanol, the more 
severe motor octane number (MON) rating is only increased about 2 ON. 

(226.231.232) Road octane numbers, which are measured in vehicle 

tests, are found to be between the RON and MON values, and 10% 

226 

methanol in unleaded gasoline gives about a 3 ON boost here. 

Fuel volatility is also affected by mixing methanol with 
gasoline. Distillation tests show a more rapid distillation at the 

lower temperatures for alcohol-gasoline blends compared with gasoline 

, 222,226,232 ml . „ . ^ J ^ , 

alone. This despression of the front end of the 

distillation curve can affect vehicle starting characteristics and 

233 

may allow for use of heavier components in the base gasoline. 

The Reid Vapor Pressure of methanol-gasoline blends is higher than 

either methanol-or gasoline-vapor pressures, and this may indicate 

226,232 

an increased tendency for vapor-lock problems. 

Methanol-gasoline blends are known to be extremely sensitive 
to the presence of small (—*0.1%) quantities of water. The water can 
cause the separation of the blend resulting in the settling of a 
water-methanol mixture to the bottom of the storage container 

(222.225.226.232) . T he presence of higher alcohols can help 

alleviate this phase separation, but quantities on the order of 

several percent are required. While some vehicle-test programs have 

233 

not shown any problems with phase separation, others have 

exhibited engine stall attributed to methanol separation in the 

226 

carburetor bowl. Large-scale use of methanol-gasoline blends 

would require special water-free bulk distribution, vehicle-storage 
and carburetor-bowl facilities to minimize moist air intrusion. 

Attention has also been given to comparisons of engine 
performance, fuel economy and emissions between vehicles fueled with 
gasoline and those fueled with gasoline-methanol blends. If the 


231 


vehicle carburetor is not adjusted, then the addition of methanol to 

the gasoline causes a leaner overall stoichiometry. In this case 

Federal-Test-Cycle evaluations with 107, methanol indicate a 507. 

reduction in CO, a 10% reduction in NO , very little change in 

x 

unburned hydrocarbons, and a 10% reduction in miles-per-gallon fuel 

231 234 

economy. Other road tests also show the CO reduction, but do 


not give consistent fuel economy results. Both slight improvements 

, 226 
and slight losses in fuel economy have been reported. While some 

road programs do not report driveability problems with methanol 
233 


234 


blends, other groups (with substantial driveability evaluation 

experience) report significant driveability degradation with methanol 
226,231 

blends. Since the addition of methanol without carburetor 

adjustment does lean the mixture, we would expect lean misfire 
driveability problems on late-model engines which are already 
adjusted close to the lean limit. Addition of methanol and adjustment 
of the carburetor to maintain stoichiometry would undoubtedly 
compromise the above-mentioned CO emissions reduction. Federal-Test- 
Procedure data for methanol-gasoline blends is shown in Figure 13.2 
and Table 13.3. 

Recent evidence indicates that vehicle fuel-tank and 
distribution systems may experience severe corrosion problems with 


226 


methanol-gasoline blends. 

In summary, methanol-gasoline blends can be used in conventional- 
type engines provided carburetors are adjusted to maintain driveability. 
Some reduction in CO emissions may result, but other emissions and 
fuel economy will not be significantly altered. Careful attention must 
be given to bulk fuel-distribution and storage systems and vehicle 
fuel systems to avoid problems of phase separation and corrosion. 


13.6 Reformed Fuels 

The addition of small amounts of hydrogen to normal fuel systems 



NO (g/mi) HC (g/mi) 


232 




2.0 


1.0 


0.0 


CT> 

a 

e. 

> 

o 

z 

o 

o 

LU 


LU 

z> 


101 — 


8 - 


0 


c 

o 

o 

c 

o 

c 

c 

o 


o 

c 

o 

00 

<2 

Si -c 

V 

SS f 

o 

00 

\p 

0 s * 

o 

ro 

.c 


T- UJ 

o “ 


T- 

UJ 



- 2 





O 


O 

C 

a: 

-C 

+-> 

CD 


FIGURE 13.2 Emissions Data for Alcohol-Gasoline Blends, 1975 Federal 
Test Procedures, 455 CID 1973 Engine with No Carburetion Adjustment. 


Source: Reference 234 


















































233 


TABLE 13.3 


Test Data for 157, Methanol-Gasoline Blend 

Exhaust Emissions, g/mi. 

Fed. Test Procedure 


HC 

CO 

NO 

X 

Formaldehyde 

1967 Car Gasoline 

5.2 

83 

6.4 

0.13 

Gasoline + 157> methanol 

3.8 

41 

8.1 

0.20 

1973 Car Gasoline 

1.1 

21 

2.6 

0.075 

Gasoline + 15% methanol 

1.1 

8 

1.7 

0.10 

"1975 Car" Gasoline 

0.10 

0.3 

2.6 

0.002 

Gasoline + 15% methanol 

0.10 

0.4 

2.3 

0.004 

1977 Federal Standards 

0.4 

3.4 

1.5 





Car 



1967 


1973 

"1975" 


(Rich) 


(Lean) 

Catalyst Equipped 

Gasoline, mpg 

14.3 


11.2 

11.4 

Gasoline + 15% methanol, mpg 

14.4 


10.6 

10.9 

7 0 Change, mpg 

+1 


-6 

-4 

% Change, miles/Btu 

+8 


+1 

+3 


Notes 

1) Engines - 1967 289 CID V-8, air-gasoline equivalence ratio 0.9 

1973 351 CID V-8, air-gasoline equivalence ratio 1.05 
M 1975"351 CID V-8, air-gasoline equivalence ratio 1.0 

2) Carburetion was adjusted for gasoline-air mixtures and not changed 
for blends. 

3) The "1975" car was equipped with a catalytic converter. 


REF 206 












234 


(hydrogen-supplemented fuel) can extend the lean misfire limit for 

spark-ignited, reciprocating engines to quite lean stoichiometry. Such 

lean mixtures result in significant improvements in engine thermal 

efficiencies and very low NO and CO emissions, but usually result 

x 

in higher unburned hydrocarbon emissions. One concept for obtaining 

the required hydrogen involves reforming a portion of the gasoline to 

hydrogen and carbon monoxide by means of an on-board partial oxidation 

reforming unit. It is also possible to reform other fuels, such as 
235 

methanol, to obtain the hydrogen required. In this subsection 
we review recent work with such hydrogen-supplemented fuel systems. 

The effect of adding various amounts of hydrogen to single and 

multicylinder gasoline-fueled engines has been investigated at 

220 

General Motors Research Laboratories. Relatively small amounts of 
hydrogen give dramatic reductions in the lean limit. In a single¬ 
cylinder engine, a mixture of 5% and 95% iso-octane (by mass) 
extends the lean limit from an equivalence ratio ($) of 0.9 to about 
0.7, while 107 o lowers the limit to $ = 0.5. With enough hydrogen 
added to run at an equivalence ratio of 0.55, NO and CO emissions 
are negligible, and unburned hydrocarbons are about the same as 100% 
iso-octane at $6 = 1. Under the same conditions, thermal efficiency 

increases from 33% at <k> = 1 to 37%. at <f> - 0.55, while the power 

220 

output drops about 30%. 

Vehicle tests with hydrogen-supplemented fuel were also carried 
220 

out. In tests with constant hydrogen mass flow, emissions were 

measured using the Federal Test Procedure (hot start), and the results 
are shown in Table 13.4 below. Also shown in Table 13.4 are emissions 
obtained with a fuel-metering system which enabled the relative 
amount of hydrogen in the fuel to be held constant. The results 
indicate that lean operation with hydrogen-supplemented fuel does 
dramatically reduce CO and NO emissions, but HC emissions are 

X 

relatively high. 


235 



TABLE 13.4 


Federal Test Procedure Emissions with 
Hydrogen Supplemented Fuels. 


Emissions (g/mi) 



Constant Hydrogen Mass Flow 

Constant Hydrogen Fraction 

NO 

1.3 

0.39 

X 



CO 

5.6 

3.3 

HC 

2.6 

3.1 



REF 220 


The initial hydrogen-supplemented fuel concept arose at Jet 
Propulsion Laboratory (JPL) and a large program is underway there. 
Single and multicylinder engine tests with added hydrogen confirm the 
results noted above. The current reformer unit is a homogeneous, 
partial-oxidation type, operating without water feed at 81% efficiency. 
Development of catalytic-type reformers is also underway. The 
catalytic reformers operate at much lower temperatures than the 
homogeneous type and do not have the soot formation tendency. However, 
they must be warm to function properly and require prevaporized fuel. 

Limited vehicle tests with reformer-type products added to the 
gasoline have been carried out at JPL. While the emissions results 
were impressive on these tests, it was difficult to determine how 
much improvement was due to the supplemented fuel and how much was 
attributable to improved fuel vaporization and distribution due to the 
use of a special atomizing carburetor. Such carburetors are known to 
make leaner operation possible. 

The reformed fuel concept is an attractive way to achieve the 
lean operation required for low emissions and good fuel economy. 
Reformer development and cycle testing are required to fully 
demonstrate the system. After such demonstration, this concept should 





236 


be carefully compared with other methods for achieving overall 
lean operation. 

13.7 Other Alternative Fuels 

This subsection reviews several additional alternative fuels 
which have been suggested for their low-emissions potential. These 
fuels are all blends or emulsions containing a conventional fuel 
and/or alcohol and water. In general, much less engine test data 
is available for these compounds than for the previously discussed 
fuels. 

Water and gasoline or distillate combinations in which a 

surfactant is added to emulisfy the water have been suggested as 

engine fuels. In distillate combustion such emulsions result in a 

micro-explosion of the water droplets before combustion because the 

vapor pressure of the water is greater than the distillate vapor 

pressure. This micro-explosion should produce finer fuel sprays 

£37 

and may reduce NO and soot emissions. Gasoline's higher 

X 

volatility prevents the micro-explosion phenomenon from occuring in 

gasoline-water emulsions and any reduction in NO would be due to 

237 x 

the cooling effect of the water. Also, if the carburetor is not 

adjusted, metering the gasoline-water mixture instead of gasoline 

results in leaner engine operation. 

Limited emissions data are available from the California Air 

Resources Board (ARB) cycle tests with "Vareb-10 Fuel", a fuel made 

up of 57% Indolene, 387o Vareb emulsifier and 5% water by weight. 

Cold-start test results are given in Table 13.5, taken from 

Reference 238. CO and NO emissions were reduced, but cold-start 

x 

hydrocarbons increased. The hydrocarbon reactivity ratio also 
increased with the water gasoline emulsion. 



Effect of Vareb-10 on 
Cold-Start Emission 


237 


















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238 


Homogeneous blends of gasoline, isoprepyl or tertiary butyl 

alcohol, and water have been patented by Freeh and Tazuma of Goodyear 

239 

Research Laboratories. The blends contain about 40% alcohol, 

and water is added to the miscible range. It is proposed that these 

large quantities of alcohol would be obtained by removing propene 

and isobutene from current refinery streams and converting them to 

isopropyl alcohol or t-butyl alcohol. Only very limited vehicle-test 

data is available for these blends. California cycle tests on a 1969 

Dodge indicated reductions of 70%-80% in CO, 30%-45% in H/C, and 

25%-30% in NO . Fuel economy was not measured. Increases of about 
x 

3 RON per 10% alcohol are claimed for the blends. More vehicle- 
test data and an analysis of the refining costs are necessary for a 
full evaluation of the potential for these blends. In particular, 
tests on late-model vehicles are not expected to show as large 
an emissions reduction as noted above. 

A water/methanol gasoline blend, in which a surfacant is 

used to obtain a stable emulsion of the water/alcohol in the gasoline, 

240 

has been suggested as a emissions reducing fuel. Tests using a 

7.5% methanol, 2% surfacant, 0.5% water, 90% gasoline fueled 1973 
vehicle (360 CID, A/F = 15.5:1, CR = 8.5:1) quite similar to previously 
discussed methanol-gasoline blends. The leaning effect reduced CO 
substantially but HC, NO and fuel economy were not significantly 
changed. The use of a surfactant to increase the water tolerance 
of methanol-gasoline blends is noteworthy. If such a compound were 
economically available in large quantities, it might help solve the 
water sensitivity problem and make the use of gasoline-methanol 
mixtures more attractive. 



REFERENCES 


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239 





240 


17. Data presented to the Panel of Consultants on Engine Systems by 
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241 


33. Statement by Volkeswagenwerk AG during Presentations of Foreign 
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May 10, 1974. 

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John (Consultant to Committee on Motor Vehicle Emissions^, 

August 7, 1974. 



242 


48. Visit to Ford Motor Co. by CMVE consultants, May 1974. 

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50. CMVE Technology Panel meeting with General Motors Corp., Techni¬ 
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53. Presentation by Toyota Motor Co. during Presentations of 
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243 


64. Wulfhorst, D. , Trip Report of visit to Toyo Kogyo Co., Ltd., 

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244 


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245 


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101. Perkins Engines presentation to CMVE consultants, June 1974. 

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106. Caplan, John D., "Smog Chemistry Points the Way to Rational 
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246 


110. Ford Motor Co. presentation to CMVE consultants, May 1974. 

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Hearings, Subcommittee on Air and Water Pollution, Committee on 
Public Works, U.S. Senate, 93rd Congress, 1st Session, May 14, 

17, 18, and 21, 1973, Serial No. 93-H9, p 956. 

116. An Evaluation of Alternative Power Sources for Low Emission 
Automobiles , Report of the Panel on Alternate Power Sources to 
the Committee on Motor Vehicle Emissions, National Academy of 
Sciences, April 1973. 

117. Brogan, John J., "Alternative Powerplants," Advanced Automotive 
Power Systems Development Division, U.S. Environmental Protection 
Agency, IECEC, 1973. 

118. _"The automobile truck sector of transportation," 

Public Address, May 1974. 

119. Eltinge, Lamont, "1970's Development of 21st Century Mobile- 
Dispersed Power, A Challenge Requiring New Technical Solutions and 
Systems-Management," Eaton Corporation, 1973. 

120. Breele, Y. , "Using hydrogen fuel cells for urban transportation," 

SAE Automotive Engineering Congress, Detroit, MI, February 1974. 

121. Brobeck, William M., "The still engine as an automotive powerplant," 
William M. Brobeck & Associates Paper, Berkeley, CA. 

122. Visit to General Motors Corp., Warren, MI by CMVE consultants, 
February 14, 1974. 

123. Pompei, Francesco, and Joseph Gerstmann, "N0 X production and control 
in a premixed gasoline fired combustion system," paper presented at 
the 75th National Meeting of the American Institute of Chemical 
Engineers, Detroit, MI, June 3-6, 1973. 






247 


124. Rogo, Casimir and Richard L. Trauth, 'Design of high heat release 
Slinger combustor with rapid acceleration requirement," SAE 
Automotive Engineering Congress, Detroit, MI, February 1S74. 

125. Zwick, E.B., and R.D. Bottos, "Development of Low Emission Combus¬ 
tion System for the MERDC 10KW Turbo-Alternator," Zwick Co., May 1974. 

126. Zwick Co., Santa Ana, CA, 4/11/74. 

127. Solar, San Diego, CA, 4/10/74. 

128. Jet Propulsion Laboratory, Altadena, CA, 4/9/74. 

129. Ford Motor Co., Dearborn, MI, 2/13/74 -- gas turbines, Stirling 
engines. 

130. Chrysler Corp., Detroit, MI, 2/12/74 -- gas turbines. 

131. Williams Research, Detroit, MI, 3/27/74 -- gas turbines. 

132. Walzer, P., R. Buchheim, P. Rottenkolber, G. Hagemann, "Pas¬ 
senger Car Performance with the Experimental Gas Turbine VW--GT 70," 
ASME Publication 74-GT108. 

133. Buchheim, Rolf, "Das Emissionsverhalten der Personenwagen- 
Gasturbine VW-GT 70," Wolfsburg, MTZ Motortechnische Zeitschrift 
35, 1974. 

134. Walzer, Peter, Paul Rottenkolber, Gunter Hagemann, "Die Personnen- 
wagen-Versuchsgasturbine VW-GT 70," Wolfsburg, Sonderdruck aus 
MTZ Motortechnische Zeitschrift 34. Jahrgang, Franckh'sche 
Verlagshandlung Stuttgart, Nummer 9/19/73. 

135. Klarhoefer, C, "Optimization of the Idling and Acceleration 
Characteristics of a Vehicular Gas Turbine by Analog Simulation," 

ASME Publication 74-GT-103. 

136. Forschungsbericht, Nr. F3-73/18 , Research Work at Volkswagen on 
Gas Turbines. 

137. Sheridan, David C., Gary E. Nordenson, and Charles A. Amann, 

"Variable compressor geometry in the single-shaft automotive 
Turbine Engine," SAE Automotive Engineering Congress, Detroit, MI, 
February 1974. 

138. Sanders, William A. and Hubert B. Probst, "Behavior of ceramics 
at 1200° C in a simulated gas turbine enviornment," Ibid . 




248 


139. Beck, Robert J., "Evaluation of ceramics for small gas turbine 
engines," Ibid . 

140. Torti, M.L., "Ceramics for gas turbines, present and future," 

Ibid . 

141. Bratton, R.J., A.A. Holden and S.E. Mumford, "Testing ceramic stator 
vanes for industrial gas turbines," Ibid . 

142. Noda, Fumiyoshi, "Aluminum nitride and silicon nitride for high 
temperature gas turbine engines," Ibid. 

143. Wolkswagenwerk AG, Wolfsburg, W. Germany, 5/24/74 -- gas turbines. 

144. Environmental Protection Agency, Ann Arbor, MI, 1/22-23/74. 

145. Brobeck Associates, Berkeley, CA, 4/8/74 -- steam engine. 

146. Steam Power Systems, San Diego, CA, 4/10/74 -- steam engine. 

147. Jay Carter Enterprises, Burkburnett, TX, 4/12/74 -- steam engine. 

148. Scientific Energy Systems, Watertown, MA, 3/8/74 -- steam engine. 

149. Termo-Electron Corp., Waltham, MA, 3/8/74 -- organic Rankine cycle. 

150. Teagan, W.P., and W. Clay, "3 KW Closed Rankine-Cycle Powerplant 

with a Turbine Expander," Final Report, prepared for US Army ^ 

Mobility Research and Development Center, Electromechanical 
Division, Ft. Belvoir, VA, Contract No. DAAK 02-72-C-0554, 

Section E, Item #0002, Exhibit A, Item A005, Thermo-Electron 
Corp., Waltham, MA, September 1973. 

151. Hodgson, J.N., and F.N. Collamore, "Turbine Rankine cycle auto¬ 
motive engine development," SAE Automotive Engineering Congress, 
Detroit, MI, February 1974. 

152. Hoagland, L.C. (Scientific Energy Systems Corp., Watertown, MA) 
in letter to J.W. Bjerklie (CMVE consultant), March 19, 1974. 

153. Hoagland, L.C., R.L. Dernier, and J. Gerstmann, "Design features 

and initial performance data on an automotive steam engine. Part I - 
overall powerplant description and performance," SAE Automotive 
Engineering Congress, Detroit, MI, February 1974. 

154. Syniuta, W.D. and R.M. Palmer, "Design features and initial per¬ 
formance data on an automotive steam engine, Part II - reciproca¬ 
ting steam expander - design features and performance, Ibid. 







249 


155. Patel, P., E.F. Doyle, R.J. Raymond, and R. Sakhuja, "Automotive 
organic Rankine-cycle powerplant - design and performance data, 

Ibid . 

156. Dutcher, Cornelius G., Remarks before the Subcommittee on Space 
Science and Applications of the Committee on Science and Astro¬ 
nautics of the U.S. House of Representatives, February 6, 1974. 

(Mr. Dutcher is with Steam Power Systems, San Diego, CA.) 

157. Carter, Jay (Jay Carter Research and Development Engineers, 

Burkburnett, TX) in letter to J.W. Bjerklie, May 19, 1974. 

158. Minto, Wallace L. (President, Kinetics Corp., Sarasota, FL) in 
letter to J.W. Bjerklie, March 15, 1974. 

159. Keller, Leonard J. (President, The Keller Corp., Dallas, TX) in 
letter to J.W. Bjerklie, March 22, 1974. 

160. The Keller Corp. Memorandum, "External Combustion Engine Systems - 
Recent developments and comments on state of the art," November 22, 

1971. 

161. Nichols, W.P. (President, Paxve, Inc., Costa Mesa, CA) in letter 
to Emerson W. Pugh, Executive Director, CMVE), April 3, 1974. 

162. Younger, Francis C., "Characteristics of the Brobeck steam bus 
engine," SAE National West Coast Meeting, San Francisco, CA, 

August 21, 1972. 

163. Richardson, R.W., "Automotive Engines for the 1980's, Eaton's 
Worldwide Analysis of Future Automotive Power Plants, Eaton Corp., 
Southfield, MI, July 1973. 

164. _, Statement to the Subcommittee on Space Science 

and Applications of the Committee on Science and Astronautics, U.S. 

House of Representatives, June 13, 1974. 

165. Philips Research Labs, Eindhoven, Holland, 5'20/74 -- Stirling engines. 

166. United Stirling, Malmo, Sweden, 5/21/74 -- Stirling engines. 

167. MAN-MWM, Augsburg, W. Germany, 5/22/74 -- Stirling engines. 

168. Kinergetics, Tarzana, CA, 4/11/74 -- Stirling engine. 

169. Postma, Norman D., Rob Van Giessel and Frits Reinink, "The Stirling 
engine for passenger car application," SAE Combined Commercial \ehicle 
Engineering & Operations and Powerplant Meetings, Chicago, IL, June 1973. 




250 


170. Carlqvist, S.G, and L.G.H. Ortegren, "The potential impact of the 
Stirling engine on environmental issues," prepared for presenta¬ 
tion to The Institute of Road Transport Engineers, January 1974. 

171. van Beukering, H.C.J. and H. Fokker, "Present state-of-the-art 
of the Philips Stirling engine," SAE Combined Commercial Vehicle 
Engineering & Operations and Powerplant Meetings, Chicago, IL, 

June 1973. 

172. Aim, C.B.S., S.G. Carlqvist, P.F. Kuhlmann, K.H. Silverqvist, 
and F.A. Zacharias, "Environmental characteristics of Stirling 
engines and their present state of development in Germany and 
Sweden," 10th International Congress on Combustion Engines, Paper 
No. 18, 1973. 

173. Kuhlmann, Peter, Das Kennfeld des Stirlingmotors , Augsburg, M.A.N. 
Sonderdruck aus MTZ Motortechnische Zeitschrift, 34. Jahrg., 

Nr. 5/1973. 

174. Asselman, G.A.A., J. Mulder, and R.J. Meijer, "A High-Performance 
Radiator," Philips Research Labs., Eindhoven (The Netherlands), 
1972. 

175. "Hydorgen Safety of the Stirling Engine," Stanford Research Insti¬ 
tute, Menlo Park, CA, January 4, 1974. 

176. Stein, Robert A., "Progress Report on the Development of the 
Valved Hot-Gas Engine," M. Thesis, ME Dept., MIT, January 1974. 

177. MIT, Boston, MA, 3/8/74 -- reciprocating Brayton engine. 

178. Brobeck Associates, Berkeley, CA, Op. Cit . 

179. Post, Richard F. and Stephen F., "Flywheels," Scientific American , 
CCXXIX, No. 6, December 1973, p. 17. 

180. Friedman, Donald and Jerar Andon, "The Characterization of Battery- 
Electric Vehicles for 1980-1990," Minicars, Inc., Golata, CA, 
submitted by General Research Corp., Prime Contract No. EPA- 
68-01-2103, January 1974. 

181. Hamilton, William F., "Use of Electric Cars in the Los Angeles 
Region 1980-2000," Preliminary draft RM1891 (EPA sponsored Elec¬ 
tive Car Impact Study), General Research Co., Santa Barbara, CA, 
April 1974. 





251 


182. Foote, L.R., D.R. Hamburg, J.E. Hyland, C.W. Koop, W.H. Koch, and 
L.E. Unnever, "Electric Vehicle Systems Study," Technical Report 
No. SR-73-132, October 25, 1973, Ford Motor Co.,(Abbreviated ver¬ 
sion: See Ref. 183.) 

183. Unnever, Lewis, "Electric vehicle systems study," Paper No. 7414, 
Third International Electric Vehicle Symposium, Washington, DC, 
February 19-22, 1974, (UNIPEDE) (More detailed version: See Ref. 
182.) 

184. Hagey, Graham and William F. Hamilton, "Impact of electric cars 
for the Los Angeles Intrastate Air Quality Control Region," 

Paper No. 7470, Ibid . 

185. Bader, C., and H.G. Plust, "Electrical propulsion systems for 
Road Vehicles; State of the Art and Present Day Problems," Paper 
No. 7478, Ibid. Also, Elektrische Antriebe fur Straszenfahrzeuge, 
ETZ-A , 11,637 (1973). 

186. "How Ford Evaluates Three Types of Electric Vehicles," Automotive 
Engineering, LXXXII, No. 6, pp. 37-41, 75, June 1974. 

187. Busi, James D., and Lawrence R. Turner, "Current Developments in 
Electric Ground Propulsion Systems, R&D Worldwide," Journal of the 
Electrochem. Soc ., CXXI, 183C, June 1974. 

188. Healy, Timothy J., "The Electric Car: Will It Really Go?" IEEE 
Spectrum , April 1974. 

189. Linnenbom, V.J., "Battery Powered Buses in London," Office of 
Naval Research, European Scientific Notes, ESN028-6, June 28, 1974. 

190. Gross, Sidney, "Review of candidate batteries for electric vehicles," 
Battery Council International, preprint, Annual Meeting, London, 

May 12-17, 1974. 

191. Kamada, K., I. Okazaki, and T. Takagaki, "New lead acid batteries 
for electric vehicles and approach to their evaluation method," 

Paper No. 7429, Third International Electric Vehicle Symposium, 
Washington, DC, February 19-22, 1974, (UNIPEDE). 

192. "Research on Electrodes and Electrolyte for the Ford Sodium- 
Sulfur Battery," Quarterly Report, Scientific Research Staff, 

Ford Motor Co., NSF Contract NSF-C805, January 1-March 1, 1974. 

193. Sudworth, James L., "Some Aspects of Sodium Sulfur Battery Design," 
Preprint, 1974. 









252 


194. Appleby, A.J., J.J. Pompon, and M. Jacquier, "Zinc-air batteries 
in vehicular applications," Paper No. 7430, Third International 
Electric Vehicle Symposium, Washington, DC, February 19-22, 1974, 
(UNIPEDE). 

195. Nelson, P.A., A.A. Chilenskas, R.K. Stuenenberg," The Need for 
Development of High Energy Batteries for Electric Automobiles," 
ANL-8075 (DRAFT), Argonne National Laboratory, January 1974. 

196. Salihi, Jalal T., "Energy Requirements for Electric Cars and 

Their Impact on Electric Power Generation and Distribution Systems," 
IEEE Transactions on Industry Applications , "Vol. IA-IX, No. 5, 
September/October 1973. 

197. Altendorf, J.P., A. Kaberlah and N. Saridakis, "A comparison 
between a pick-up van with internal combustion engines and 

an electric pick-up van," Paper No. 7445, Third International 
Electric Vehicle Symposium, Washington, DC, February 19-22, 1974, 
(UNIPEDE). 

198. Wouk, Victor and Charles L. Rosen, "Preliminary evaluation E.P.A. 
test on PEM hybrid preliminary 'improvement package' information 

for Phase II, F.C.C.I.P.," Paper No. 9336 Preliminary, April 4, 1974. 

199. Mapham, Neville, "Conservation of petroleum resources by the use 
of electric cars," preprint 740171, SAE Automotive Engineering 
Congress, Detroit, MI, February 25-March 1, 1974. 

200. Austin, A.L., "A Survey of Hydrogen's Potential as a Vehicular 
Fuel," Lawrence Livermore Laboratory, Report No. UCRL-51228, 

June 1972. 

201. Pangborn, J.B., and J.C. Gillis, "Feasibility Study of Alternative 
Fuels for Automotive Transportation," Institute of Gas Technology, 
Interim Report on Contract No. 68-01,211, presented at AAPS 
Coordination Meeting, May 1974. 

202. Discussions with J. Pangborn (IGT), August 15, 1974. 

203. Kant, F.H., "Feasibility Study of Alternative Automotive Fuels," 
Exxon Research and Engineering Co., Report No. EPA-460/3-74-009, 

June 1974. 

204. Jaffe, H., et al . , "Methanol from Coal for the Automotive Market," 
USAEC, February 1974. 

205. Wentworth, T.O., as quoted in "Outlook Bright for Methyl-Fuel," 
Environmental Science and Technology , VII, 1973, p. 1002. 





253 


206. Dutkiewicz, B. , "Methanol Competitive with LNG on Long Haul," 

The Oil and Gas Journal , April 30, 1973, p. 166. 

207. "Coal Technology: Key to Clean Energy," Annual Report 1973-74, 
Office of Coal Research, U.S. Department of the Interior. 

208. Mills, G. and B. Harney, "Methanol - the 'New Fuel' from Coal," 
Chemtech , January 1974, pp. 26-31. 

209. Hammond, A., "A Timetable for Expanded Energy Availability," 
Science , CLXXXIV, (1974), p. 367. 

210. Hord, J., "Cryogenic H2 and National Energy Needs," presented at 
Cryogenic Engineering Conference, August 1973. 

211. Billings, R. , "Hydrogen Storage for Automobiles Using Metal Hy¬ 
drides and Cryogenics," presented at the Hydrogen Economy Miami 
Energy (THEME) Conference, March 1974. 

212. "Proceedings of the Hydrogen Economy Miami Energy (THEME) 
Conference," Section 4, Metal Hydride Storage; Section 8, Hydrogen 
Storage in Vehicles, March 1974. 

213. King, R., et al ., "The Hydrogen Engine: Combustion Knock and the 
Related Flame Velocity," Transactions Engineering Institute of 
Canada , II, No. 4, (1958), p. 143. 

214. de Boer, P., W. McLean, J. Fagelson, and H. Homan, "An Analytical 
and Experimental Study of the Performance and Emissions of a 
Hydrogen Fueled Reciprocating Engine," 9th IECEC, San Francisco, 
August 1974. 

215. Billings, R. and F. Cynch, "Performance and Nitric Oxide Control 
Parameters of the Hydrogen Engine," Energy Research Publication 
73002, Provo, Utah, April 1973. 

216. Finegold, J., et al ., "The UCLA Hydrogen Car: Design, 
Construction and Performance," SAE Paper No. 730507 (1973). 

217. _, and M. Van Vorst, "Engine Performance with Gasoline 

and Hydrogen: A Comparative Study," presented at the Hydrogen 
Economy Miami Energy (THEME) Conference, March 1974. 

218. Adt, R., et al ., "The Hydrogen-Air Fueled Automobile," Proceed ¬ 
ings 8th IECEC , (1973), p. 194. 













254 


219. Murray, R. , R. Schoeppel and C. Gray, "The Hydrogen Engine in 
Perspective," Proceedings 7th IECEC , San Diego, September 1972. 

220. Stebar, R. and F. Parks, "Emission Control with Lean Operation 
Using Hydrogen - Supplemental Fuel," SAE Paper No. 740187, 

February 1974. 

221. "Alcohols and Hydrocarbons as Motor Fuels," SP-254, Society of 
Automotive Engineers, Inc c , New York, June 1964. 

222. Bolt, J., "A Survey of Alcohol as a Motor Fuel," Op Cit ., p. 1. 

223. Adelman, H., D. Andrews and R. Devoto, "Exhaust Emissions from a 
Methanol-Fueled Automobile," SAE Transactions , Paper No. 720693 
(1972). 

224. Ingamells, J., "Discussion of SAE Papers 720692 and 720693," 

SAE Transactions , (1972), p. 2108. 

225. Discussions with R. Hurn, U.S. Bureau of Mines, Bartlesville 
Energy Research, April 11, 1974. 

226. Ingamells, J. and R. Lindquist, "Methanol as a Motor Fuel," sub¬ 
mitted by Chevron Research Co., (to be published in Science ). 

227. Starkman, E., H. Newhall and R. Sutton, "Comparative Performance 
of Alcohol and Hydrocarbon Fuels," Reference 221, p. 14. 

228. Ebersole, G. and F. Manning, "Engine Performance and Exhaust 
Emissions: Methanol versus Isoctane," SAE Transactions , Paper 
No. 720692 (1972). 

229. Pefley, R., M. Saad, M. Sweeney, and J. Kilgroe, "Performance 
and Emission Characteristics Using Blends of Methanol and Dis¬ 
sociated Methanol as an Automotive Fuel," Proceedings of 6th 
IECEC , (1971), p. 36. 

230. Reed, T. and R. Lerner, "Methanol: A Versatile Fuel for Immediate 
Use," Science , CVXXXII, (1973), p. 1299. 

231. Gallopoulos, N., "Alternate Fuels for Automobiles," General 
Motors Research Laboratory, data submitted during panel of consul¬ 
tants visit March 29, 1974. 

232. "Use of Alcohol in Motor Gasoline - A Review," American Petroleum 
Institute, API Publication No. 4082, Washington, DC (1971). 











255 


233. Reed, T., personal communication, May 1974. 

234. Lerner, R.M., et al ., "Improved Performance of Internal Combus¬ 
tion Engines Using 5-207 o Methanol," (to be published). 

235. NASA Lewis Research Center, Hydrogen Generator Program, informa¬ 
tion provided during site visit, April 1974. 

236. Breshears, R., H. Cotrill and J. Rupe, "Partial Hydrogen Injec¬ 
tion into Internal Combustion Engines, Effect on Emissions and 
Fuel Economy," Jet Propulsion Laboratory Project Briefing, 

February 1974. 

237. Discussions with Dr. Fred Dryer, Princeton University, August 16, 
1974. 

238. "Evaluation of Vareb-10 Fuel Mixture," California Air Resources 
Board, January 1974. 

239. Freeh, K.J., and J.J. Tazuma, U.S. Patent No. 3822119. Also, 
discussions with Dr. James Tazuma, Goodyear Research Laboratories, 
August 16, 1974. 

240. "Water/Alcohol Solutions in Internal Combustion Engine Fuel 
Systems," Emission Free Fuels, Sparta, NJ, December 1973. 



APPENDIX A 


Organizations Contacted by Members of the 

Panel of Consultants on Engine Systems 


1. Ford Motor Co., Dearborn, MI 

2. Chrysler Corp., Detroit, MI 

3. Environmental Protection Agency, 

Ann Arbor, MI 

4. Chrysler Corp., Detroit, MI 

5. Ford Motor Co., Ann Arbor, MI 

6. General Motors Corp., Warren, MI 

7. California Air Resources Board, 

Los Angeles, CA 

8. Dresser Industries, Santa Ana, CA 


9. 

Philco-Ford, Newport Beach, 

CA 

10. 

New York City Air Resources 
New York, NY 

Board, 

11. 

Curtiss-Wright Corp., Wood-Ridge, NJ 

12. 

Texaco, Inc., Beacon, NY 


13. 

Universal Oil Products, 

Des Plaines, IL 


14. 

Bendix, Detroit, MI 


15. 

Ethyl Corp., Ferndale, MI 


16. 

Holley Carburetor, Detroit, 

MI 

17. 

Yanmar Diesel, Osaka, Japan 



1/17/74 

*John 


1/17/74 

John 


1/23/74 

John 


2/12/74 

John 


2/13/74 

John 


2/14/74 

John 


3/20/74 

John 


3/21/74 

John 


3/21/74 

John, 

Newhall 

3/26/74 

John 


3/27/74 

John, 

Wulfhorst 

3/28/74 

John 


4/16/74 

John, 

Jost 

5/7-8/74 

John, 

Jost 

5/7-8/74 

John, 

Jost 

5/7-8/74 

John, 

Jost 

5/9/74 

Wulfhorst 


*Last names of members of the Panel of Consultants on Engine Systems 


256 





257 


18. 

Toyo Kogyo Co., Ltd., 

Hiroshima, Japan 

5/10/74 

Wulfhorst 

19. 

General Motors Corp., Warren, MI 

5/15/74 

John, Newhall 

20. 

Ford Motor Co., Dearborn, MI 

5/16/74 

John, Newhall 

21. 

Chrysler Corp., Detroit, MI 

6/4/74 

John 

22. 

TACOM, Detroit, MI 

6/4/74 

John 

23. 

Questor Corp., Toledo, OH 

6/6/74 

John 

24. 

Shell Research Ltd., Thornton, England 

6/14/74 

John 

25. 

Ricardo & Co. Engineers, Ltd., 
Shoreham-by-the-Sea, England 

6/17/74 

John, Henein, Jost 

26. 

British Leyland Ltd., 

Coventry, England 

6/18/74 

John, Jost 

27. 

C.A.V., London, England 

6/18/74 

Henein 

28. 

Toyo Kogyo Co., Ltd., 

Hiroshima, Japan 

6/18/74 

N ewha11 

29. 

Toyota Motor Co., Ltd., Aichi, Japan 

6/18/74 

Newhall 

30. 

Honda R&D Co., Ltd., Saitama, Japan 

6/19/74 

N ewha11 

31. 

Perkins Engine Co., 

Petersborough, England 

6/19/74 

Henein 

32. 

Volkswagenwerk AG, 

Wolfsburg, W. Germany 

6/19/74 

John, Jost 

33. 

Daimler-Benz AG, Stuttgart, W. Germany 

6/20/74 

John, Henein, Jost 

34. 

General Motors Technical Center, 

Warren, MI 

6/20/74 

Wulfhorst 

35. 

Japan Motor Vehicle Research 

Laboratory, Osaka, Japan 

6/20/74 

Newha11 

36. 

Nissan Motor Co., Ltd., Tokyo & 
Yokosuka, Japan 

6/20/74 

Newhall 


258 


37. 

Daihatsu Kogyo Co., Ltd., Osaka, 

Japan 6/21/74 

Newhall 

38. 

Robert Bosch GMBH, Postfach, W. 

Germany 6/21/74 

John, 

Henein 

39. 

Audi, Ingolstadt, W. Germany 

6/22/74 

John, 

Jost 

40. 

Ford Motor Co., Dearborn, MI 

7/9/74 

Newhall 

41. 

Gould, Inc., Cleveland, OH 

7/9/74 

John 


42. 

General Motors Corp., Warren, MI 

8/1/74 

John 



259 


APPENDIX B 


Organizations Contacted by Members of the 

Panel of Consultants on Alternatives 


1 . 

Environmental Protection Agency, 
Ann Arbor, MI 


1/22-23/74, 
3/27/74, 7/2/74 

*Bjerklie, Tobias 

2. 

ACAAPS Review Meeting, Washington, 

DC 

2/11/74 


Bjerklie 

3. 

Chrysler Corp., Detroit, MI 


2/12/74, 

3/28/74 

Bjerklie, McLean, 
Wilson 

4. 

Ford Motor Co., Dearborn, MI 


2/13/74, 

3/28/74 

Bjerklie, McLean, 
Wilson 

5. 

General Motors Corp., Warren, MI 


2/14/74, 

3/26/74 

Bjerklie, Tobias 

6. 

Society of Automotive Engineers 
Meeting, Detroit, MI 


2/27/74 


Bjerklie 

7. 

Petro-Electric Motors, Ltd., 

New York, NY 


March 1974 

Bjerklie 

8. 

Massachusetts Institute of Technology, 
Boston, MA 

3/8/74, 
May 1974 


Bjerklie, McLean 

9. 

Scientific Energy Systems, 
Watertown, MA 


3/8/74 


Bjerklie, McLean, 
Wilson 

10. 

Thermo-Electron Corp., Waltham, MA 


3/8/74 


Bjerklie, McLean, 
Wilson 

11. 

United Stirling (Sweden) in Boston 

, MA 3/15/74 


Bjerklie 

12. 

The Hydrogen Economy Miami Energy 
(Theme) Conference, Miami Beach, 

FL 

3/18-19/74 

McLean 

13. 

Institute of Gas Technology, 
Chicago, IL 


3/25/74, 

8/15/74 

McLean 

14. 

Williams Research, Detroit, MI 


3/27/74 


Bjerklie, Wilson 


*Last names of members of the Panel of Consultants on Alternatives 





260 


15. 

16. 


17. 


18. 


19. 


20 . 


21 . 


22 . 

23. 


24. 


25. 


26. 


27. 


28. 


29. 


30. 


31. 


32. 


33. 


34. 


35 . 


Exxon Res. & Eng., Linden, NJ 

Brobeck Associates, Berkeley, CA 

Chevron Research Co., Richmond,CA 

University of California (Berkeley) CA 

Jet Propulsion Lab., Altadena, CA 

Solar, San Diego, CA 

Steam Power Systems, San Diego, CA 

Bartlesville Energy Research Center 
(U.S. Bureau of Mines) Barltesville,OK 

Kinergetics, Tarzana, CA 

Philips Petroleum, Bartlesville, OK 

Zwick Co., Santa Ana, CA 

Jay Carter Enterprises, Burkburnett,TX 

NASA Lewis Research Center, 

Cleveland, OH 

DAUG, Stuttgart, W. Germany 

British Railway Tech. Ctr., 

Derby, England 

Philips Research Labs., 

Eindhoven, Holland 

United Stirling, Malmo, Sweden 

MAN-MWM, Augsburg, W. Germany 

Volkswagenwerk AG, Wolfsburg, 

W. Germany 

Princeton University, Princeton, NJ 
Goodyear Research Labs., Akron, OH 


4/3/74 

McLean 

4/8/74 

Bjerklie 

4/8/74 

McLean 

4/8/74 

McLean 

4/9/74 

Bjerklie, McLean 

4/10/74 

Bjerklie, McLean 

4/10/74 

Bjerklie 

4/11/74 

McLean 

4/11/74 

Bjerklie 

4/11/74 

McLean 

4/11/74 

Bjerklie 

4/12/74 

Bjerklie 

4/12/74 

McLean 

5/15/74 

Bjerklie 

5/16/74 

Bjerklie 

5/20/74 

Bjerklie 

5/21/74 

Bjerklie 

5/22/74 

Bjerklie 

5/24/74 

Bjerklie 

8/16/74 

McLean 

8/16/74 

McLean 


U.S. GOVERNMENT PRINTING OFFICE: 1975- 582 419:224 



































































































































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